Nighttime Caffeine Intake Increases Motor Impulsivity

Nighttime Caffeine Intake Increases Motor Impulsivity | bioRxiv /* */ /* */ <!-- <!-- /*! * yepnope1.5.4 * (c) WTFPL, GPLv2 */ (function(a,b,c){function d(a){return"[object Function]"==o.call(a)}function e(a){return"string"==typeof a}function f(){}function g(a){return!a||"loaded"==a||"complete"==a||"uninitialized"==a}function h(){var a=p.shift();q=1,a?a.t?m(function(){("c"==a.t?B.injectCss:B.injectJs)(a.s,0,a.a,a.x,a.e,1)},0):(a(),h()):q=0}function i(a,c,d,e,f,i,j){function k(b){if(!o&&g(l.readyState)&&(u.r=o=1,!q&&h(),l.onload=l.onreadystatechange=null,b)){"img"!=a&&m(function(){t.removeChild(l)},50);for(var d in y[c])y[c].hasOwnProperty(d)&&y[c][d].onload()}}var j=j||B.errorTimeout,l=b.createElement(a),o=0,r=0,u={t:d,s:c,e:f,a:i,x:j};1===y[c]&&(r=1,y[c]=[]),"object"==a?l.data=c:(l.src=c,l.type=a),l.width=l.height="0",l.onerror=l.onload=l.onreadystatechange=function(){k.call(this,r)},p.splice(e,0,u),"img"!=a&&(r||2===y[c]?(t.insertBefore(l,s?null:n),m(k,j)):y[c].push(l))}function j(a,b,c,d,f){return q=0,b=b||"j",e(a)?i("c"==b?v:u,a,b,this.i++,c,d,f):(p.splice(this.i++,0,a),1==p.length&&h()),this}function k(){var a=B;return a.loader={load:j,i:0},a}var l=b.documentElement,m=a.setTimeout,n=b.getElementsByTagName("script")[0],o={}.toString,p=[],q=0,r="MozAppearance"in l.style,s=r&&!!b.createRange().compareNode,t=s?l:n.parentNode,l=a.opera&&"[object Opera]"==o.call(a.opera),l=!!b.attachEvent&&!l,u=r?"object":l?"script":"img",v=l?"script":u,w=Array.isArray||function(a){return"[object Array]"==o.call(a)},x=[],y={},z={timeout:function(a,b){return b.length&&(a.timeout=b[0]),a}},A,B;B=function(a){function b(a){var a=a.split("!"),b=x.length,c=a.pop(),d=a.length,c={url:c,origUrl:c,prefixes:a},e,f,g;for(f=0;f<d;f++)g=a[f].split("="),(e=z[g.shift()])&&(c=e(c,g));for(f=0;f<b;f++)c=x[f](c);return c}function g(a,e,f,g,h){var i=b(a),j=i.autoCallback;i.url.split(".").pop().split("?").shift(),i.bypass||(e&&(e=d(e)?e:e[a]||e[g]||e[a.split("/").pop().split("?")[0]]),i.instead?i.instead(a,e,f,g,h):(y[i.url]?i.noexec=!0:y[i.url]=1,f.load(i.url,i.forceCSS||!i.forceJS&&"css"==i.url.split(".").pop().split("?").shift()?"c":c,i.noexec,i.attrs,i.timeout),(d(e)||d(j))&&f.load(function(){k(),e&&e(i.origUrl,h,g),j&&j(i.origUrl,h,g),y[i.url]=2})))}function h(a,b){function c(a,c){if(a){if(e(a))c||(j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}),g(a,j,b,0,h);else if(Object(a)===a)for(n in m=function(){var b=0,c;for(c in a)a.hasOwnProperty(c)&&b++;return b}(),a)a.hasOwnProperty(n)&&(!c&&!--m&&(d(j)?j=function(){var a=[].slice.call(arguments);k.apply(this,a),l()}:j[n]=function(a){return function(){var b=[].slice.call(arguments);a&&a.apply(this,b),l()}}(k[n])),g(a[n],j,b,n,h))}else!c&&l()}var h=!!a.test,i=a.load||a.both,j=a.callback||f,k=j,l=a.complete||f,m,n;c(h?a.yep:a.nope,!!i),i&&c(i)}var i,j,l=this.yepnope.loader;if(e(a))g(a,0,l,0);else if(w(a))for(i=0;i (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0];var j=d.createElement(s);var dl=l!='dataLayer'?'&l='+l:'';j.src='//www.googletagmanager.com/gtm.js?id='+i+dl;j.type='text/javascript';j.async=true;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-M677548'); Skip to main content Home About Submit ALERTS / RSS Search for this keyword Advanced Search New Results Nighttime Caffeine Intake Increases Motor Impulsivity Erick Benjamin Saldes , Paul Rafael Sabandal , View ORCID Profile Kyung-An Han doi: https://doi.org/10.1101/2025.06.09.658656 Erick Benjamin Saldes Department of Biological Sciences, The University of Texas at El Paso , El Paso, TX, 79968, USA Find this author on Google Scholar Find this author on PubMed Search for this author on this site Paul Rafael Sabandal Department of Biological Sciences, The University of Texas at El Paso , El Paso, TX, 79968, USA Find this author on Google Scholar Find this author on PubMed Search for this author on this site Kyung-An Han Department of Biological Sciences, The University of Texas at El Paso , El Paso, TX, 79968, USA Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Kyung-An Han For correspondence: khan{at}utep.edu Abstract Full Text Info/History Metrics Preview PDF Abstract Caffeine is commonly consumed at night by shift workers and military personnel for its wake-promoting effect, yet its adverse effects on behavior remain underexplored. Here, we show that nighttime caffeine intake impairs inhibitory control in Drosophila melanogaster , resulting in impulsive motor behavior, with females more sensitive than males. This effect is independent of hyperactivity or sleep loss, as walking speed was unchanged, and artificial sleep deprivation via light or mechanical stimulation did not elicit similar deficits. Notably, daytime caffeine feeding did not impair inhibitory control, highlighting a circadian gating of caffeine’s behavioral impact. Mechanistically, we identify dopamine signaling as a key mediator of caffeine-induced impulsivity. Reduced dopamine synthesis ( pale/+ ), silencing of PAM dopaminergic neurons, or altered dopamine transporter activity ( fumin/+ ) attenuated or exacerbated caffeine-induced impulsivity. Targeted manipulations identified the dopamine D1 receptor (dDA1/Dop1R1) in the mushroom body (MB) α/β and γ lobes as essential for this effect, with γ-lobe neurons exhibiting heightened sensitivity. These findings reveal a circadian- and dopamine-dependent mechanism through which nighttime caffeine impairs behavioral inhibition. Introduction Caffeine is the most widely consumed psychoactive substance in the world, with approximately 85% of adults in the United States reporting regular use 1 . Its popularity stems from its ability to increase alertness, reduce fatigue, and improve performance, especially under conditions of sleep deprivation. For these reasons, caffeine is routinely used by shift workers, healthcare professionals, military personnel, and others who must remain vigilant during nighttime hours 2 – 8 . A growing body of research supports caffeine’s effectiveness in enhancing reaction times, vigilance, and attention in high-stress or sleep-deprived settings 4 , 9 – 12 . Despite its benefits, caffeine consumption is also associated with a range of adverse effects. At higher doses or in caffeine-sensitive individuals, it can induce anxiety, restlessness, nausea, jitteriness, and trembling 13 – 15 . Several studies have also reported that caffeine can impair fine motor control. For example, caffeine-naïve individuals have been shown to exhibit reduced hand steadiness, decreased manual dexterity, and increased performance errors following even moderate caffeine consumption 15 . These impairments may compromise motor accuracy and increase the risk of accidents or errors in occupational settings where precision is critical. Although caffeine’s physiological and behavioral effects are well established, the underlying mechanisms, particularly those contributing to caffeine-induced impairments in cognitive and motor functions, remain poorly understood. Furthermore, while most studies have focused on caffeine’s effects during daytime or on sleep loss per se, its behavioral impact following nighttime consumption remains largely unexplored, despite its widespread use among overnight shift workers. To address these knowledge gaps, we used Drosophila melanogaster as a model system to investigate how nighttime caffeine intake affects inhibitory control, a fundamental executive function responsible for suppressing inappropriate actions. Drosophila serves as a powerful genetic model for studying conserved mechanisms of neurotransmission, synaptic plasticity, and high-order functions such as learning and memory across species. In this study, we show that nighttime caffeine consumption in Drosophila impairs inhibitory control and induces motor impulsivity. This effect is sexually dimorphic, independent of hyperactivity or sleep loss, and mediated by dopamine signaling within the mushroom bodies, a neural structure involved in high-order functions such as learning, memory, and decision-making 16 – 19 . Our findings uncover a previously unrecognized risk of nighttime caffeine use and provide new insights into the neural mechanism that mediates caffeine-induced changes in behavior. Results Nighttime Caffeine Consumption Impairs Inhibitory Control To examine the effects of nighttime caffeine consumption on inhibitory control, we fed independent groups of Canton-S ( CS ) female and male flies food containing different caffeine concentrations (1, 5, 7.5, and 10 mg/ml) 20 – 22 . We then assessed their performance in the Go/No-Go test, which measures the ability to suppress movement in response to adverse conditions such as strong airflow or predator sounds, where movement could be detrimental to survival 18 , 23 . Typically, flies halt their movement in response to strong airflow, maintaining suppression until the airflow ceases. Flies with impaired inhibitory control exhibit impulsive flying, characterized by rapid movements at speeds exceeding 60 mm/sec. This behavior, quantified as a loss of inhibition event (LIE), serves as a measure of impulsivity 18 , 23 . In the absence of caffeine, both female and male flies showed strong movement suppression with negligible LIEs ( Figure 1A-B , 0 mg/ml). However, caffeine-fed flies displayed a dose-dependent increase in LIEs with females exhibiting a more pronounced response than males ( Figure 1A : Mann-Whitney; **, p < 0.005; ***, p < 0. 0.0001; n = 30-32. Figure 1B : Mann-Whitney; **, p < 0.005; ***, p < 0. 0.0001; n = 30-32). Download figure Open in new tab Figure 1. Nighttime caffeine consumption induces motor impulsivity in a dose-dependent manner. A-B. Nighttime caffeine intake increases motor impulsivity in wild-type CS females (A, purple bars) and males (B, teal bars) in a dose-dependent manner (Mann-Whitney; **, p < 0.005; ***, p < 0. 0.0001; n = 30-32). C-D. Caffeine levels per fly increase with higher caffeine concentrations in the food for both sexes. ANOVA with post hoc Tukey multiple comparison test; different letters denote statistically significant differences ( p 0.05 n = 30-32). To examine whether impulsivity correlates with caffeine levels in flies, CS flies were housed overnight on food containing varying concentrations of caffeine, and then caffeine levels were measured at the time of behavioral testing. As the caffeine dose increased, caffeine levels in both females and males rose accordingly ( Figure 1C , female: ANOVA, F 4,14 = 443.97, p < 0.0001, n = 3; Figure 1D , male: ANOVA, F 4,14 = 229.09; p < 0.0001, n = 3), linking behavioral changes to internal caffeine levels. At 1, 5, or 7.5 mg/mL caffeine, females and males showed comparable caffeine content, but at 10 mg/mL caffeine, females had significantly lower caffeine levels than males ( Figure 1C-D ). Given that caffeine-induced impulsivity was greater in females than males ( Figure 1A-B ), these findings suggest that females are more sensitive to caffeine’s effects on impulsivity. Caffeine-Induced Impulsivity is Independent of Hyperactivity To determine whether caffeine-induced impulsivity was associated with hyperactivity, we measured the walking speeds of CS females and males under baseline conditions (without airflow). Caffeine intake did not significantly affect walking speed in either females ( Figure 1E : Student t -test, p = 0.149; n = 30–32) or males ( Figure 1D : Student t -test, p = 0.070; n = 30–32). These findings indicate that the observed increase in impulsivity is not attributable to a general increase in locomotor activity. Sleep Deficits Do Not Account for Caffeine-Induced Impulsivity Caffeine is known to promote wakefulness and disrupt sleep 24 – 26 . Consistent with this, we observed significant sleep reductions in caffeine-fed flies, with females showing greater sleep loss than males ( Figure 2C : Student t -test: *, p < 0.05; ***, p < 0.0001; n = 14-15). To determine whether sleep loss contributes to motor impulsivity, we subjected CS flies to mechanical sleep disruption (MSD 27 ) or light-induced sleep disruption (LSD 28 ) during the nighttime phase and assessed their performance in the Go/No-Go assay. Neither MSD nor LSD increased LIEs in females or males ( Figure 2A , female: Mann-Whitney, ns, p > 0.05; n = 14–17; Figure 2B : Mann-Whitney: ns, p > 0.05; n = 14–17). Although LSD led to significant sleep loss in females comparable to that seen with caffeine feeding, it had no effect in males ( Figure 2D : Females: Student t -test: ***, p 0.05; n = 29). These results indicate that caffeine-induced impulsivity cannot be explained solely by sleep deficits. Download figure Open in new tab Figure 2. Nighttime sleep disruption or daytime caffeine feeding does not induce motor impulsivity. A-B. Neither nighttime mechanical sleep disruption (MSD; left panels in A and B) nor light-induced sleep disruption (LSD; right panels in A and B;) led to motor impulsivity in females or males (Mann-Whitney: ns, p > 0.05; n = 13-17). C. Caffeine-fed females and males showed comparable levels of sleep loss (Student t -test: *, p < 0.05; ***, p < 0.0001; n = 14-15). D. LSD induced significant sleep loss in females but not in males (For females, Student t -test; ***, p 0.05; n = 29). E-F. LSD did not enhance caffeine-induced motor impulsivity in either sex (ANOVA with post hoc Tukey; p < 0.05; n = 12). G-H. Nighttime (NT) lighting conditions, either darkness or constant light, did not affect caffeine-induced motor impulsivity in females or males (ANOVA with post hoc Tukey; p 0.05; n = 13-14). K-L. caffeine content per fly increased after 4 h of daytime feeding in both females and males (Student t -test or Mann-Whitney; ***, p < 0.0001; n = 3). To further test this, we examined whether combining LSD and caffeine at night would exacerbate motor impulsivity. In both sexes, LSD did not enhance the impulsivity induced by nighttime caffeine intake ( Figure 2E , female: ANOVA, F 3,47 = 96.88, p < 0.0001, n = 12; Figure 2F , male: ANOVA, F 3,47 = 76.80, p < 0.0001, n = 12), reinforcing the notion that caffeine’s effects are distinct from sleep loss. We also assessed whether nighttime lighting conditions influence caffeine-induced impulsivity. Flies exposed to constant darkness or light during caffeine intake exhibited comparable impulsivity levels ( Figure 2G , female: ANOVA, F 3,47 = 62.31, p < 0.0001, n = 12; Figure 2H , male: ANOVA, F 3,47 = 68.94, p < 0.0001, n = 12). Together, these findings suggest that caffeine’s effects on motor impulsivity are independent of both sleep loss and environmental light conditions at night. Daytime Caffeine Intake Does Not Impair Inhibitory Control To determine whether caffeine’s effect on impulsivity depends on the timing of intake, we fed flies with 10 mg/ml caffeine for 4 h during the daytime and assessed their inhibitory control. The 4-h daytime feeding regime was selected because it resulted in caffeine levels ( Figure 2K-L ) comparable to those observed in flies fed caffeine at night ( Figure 1C - 1D ). Both females and males fed with caffeine during the daytime exhibited robust inhibitory control ( Figure 2I-J , female: Mann-Whitney, p > 0.05, n = 13-14; Figure 2J , male: Mann-Whitney, p > 0.05, n = 14). These results clearly indicate that it is the timing, specifically nighttime, of caffeine intake that leads to impaired inhibitory control and motor impulsivity. Dopamine Mediates Caffeine-Induced Impulsivity Caffeine’s wake-promoting effects are known to involve dopaminergic signaling 24 , 26 . To determine whether dopamine also mediates caffeine’s impact on inhibitory control, we examined flies carrying heterozygous mutations in pale ( ple/+ ; two independent alleles), which encodes tyrosine hydroxylase, the rate-limiting enzyme in dopamine biosynthesis 29 . In the absence of caffeine, ple/+ displayed pronounced movement inhibition (data not shown). Upon caffeine feeding, ple/+ mutants retained strong movement suppression, unlike control CS flies ( Figure 3A , female: ANOVA, p = 0.001, n = 5-6; Figure 3B , male: ANOVA, p < 0.0001, n = 6), suggesting that reduced dopamine biosynthesis blocks caffeine-induced impulsivity. Download figure Open in new tab Figure 3. Caffeine-induced impulsivity requires PAM dopaminergic neurons and D1 receptor signaling. A-B. Caffeine-fed pale ( ple ) heterozygotes ( ple-1/+ and ple-2/+; purple bars – female; teal bars – male) exhibited robust movement inhibition (ANOVA with post hoc Dunnett; **, p < 0.005, ***, p < 0.0001; n = 5-6). C-D. Silencing PAM dopaminergic neurons using via tetanus toxin (TNT) light chain ( R58E02-GAL4/UAS-TNT ) abolished caffeine-induced impulsivity (Student t -test; ***, p < 0.0001; n = 10). E-F. fumin ( fmn ) heterozygotes ( fmn/+ ) displayed significantly heightened impulsivity after caffeine feeding (Student t -test; **, p < 0.005; ***, p < 0.0001; n = 8-9). G-H. Three D1 (dDA1) receptor mutant alleles ( dumb 1 , dumb 2 and dumb 4 ) showed no increase in impulsivity following caffeine feeding (ANOVA with post hoc Dunnett using CS as a control: ***, p 0.05; n = 10). To further assess the role of dopamine, we silenced PAM dopaminergic neurons, previously linked to caffeine-induced arousal 24 , using tetanus toxin (TNT). Silencing PAM neurons similarly abolished caffeine-induced impulsivity ( Figure 3C , female: Student’s t -test, ***, p < 0.0001, n = 10; Figure 3D , male: Student’s t -test, ***, p < 0.0001, n = 10), supporting the involvement of this neural cluster. As a complementary approach, we tested flies heterozygous for the dopamine transporter mutation fumin ( fmn/+ ), which increases extracellular dopamine 30 . Upon caffeine feeding, fmn/+ flies exhibited significantly elevated impulsivity levels ( Figure 3E , female: Student t -test, p = 0.002, n = 8-9; Figure 3F , male: Student t -test, p < 0.0001, n = 9), further implicating dopamine in mediating caffeine’s effect on inhibitory control. Download figure Open in new tab Figure 4. Nighttime caffeine feeding does not alter basal locomotor activity at the time of GNG testing. Caffeine-fed ple/+ (A-B; n = 5-6), fmn/+ (C-D; n = 8-9), D1 receptor mutants dumb 1 , dumb 2 and dumb 4 (E-F; n = 9-14) and D2 receptor mutant d2r (G-H; n = 10) exhibited basal locomotor activities comparable to unfed controls (Student t -test: ns, p > 0.05; n = 5-14). Dopamine D1 Receptor Mediates Caffeine-Induced Impulsivity The dopamine D1 receptor, dDA1, also known as Dop1R1, has previously been identified as a key mediator of caffeine’s wake-promoting effects 26 . To determine its role in caffeine-induced impulsivity, we examined three independent dDA1 mutant alleles ( dumb 1 , dumb 2 , and dumb 4 ) 19 , 31 . None of these mutants exhibited impulsivity following caffeine feeding, in contrast to wild-type controls ( Figure 3G , female: ANOVA, p < 0.0001, n = 9-14; Figure 3H , male: ANOVA, p 0.05; n = 10; Figure 3I , male: Student’s t -test, ns, p > 0.05; n = 10). These findings indicate that D1/dDA1, but not D2/d2R, mediates caffeine-induced impulsivity. Importantly, caffeine-induced impulsivity was not associated with hyperactivity. Walking speeds of all dopamine mutants – ple/+ (4A-B; Student t -test: ns, p > 0.05; n = 5-6), fmn/+ (4C-D; Student t -test: ns, p > 0.05; n = 8-9), dDA1 mutant alleles dumb 1 , dumb 2 and dumb 4 (4E-F; Student t -test: ns, p > 0.05; n = 9-14) and D2 mutant d2r (4G-H; Student t -test: ns, p > 0.05; n = 10) – remained comparable to their unfed controls, like CS . dDA1 is highly expressed in mushroom body (MB) neurons, which regulate complex behaviors such as learning, and memory 32 . The MB consists of three primary substructures: γ-lobes, α/β-lobes, and α’/β’-lobes. To dissect the contributions of these substructures to impulsivity, we knocked down dDA1 in each lobe using split-GAL4 drivers: MB005B (α’/β’), MB008B (α/β) and MB009B (γ). Knockdown of dDA1 in γ or α/β lobes significantly suppressed caffeine-induced impulsivity, whereas knockdown in α’/β’ lobes had no effect ( Figure 5A , female: ANOVA with post hoc Dunnett, p < 0.0001, n = 10; Figure 5B , male: ANOVA with post hoc Dunnett, p < 0.0001, n = 10). Download figure Open in new tab Figure 5. Dopamine D1 receptor (dDA1) in the mushroom body α/β and ψ neurons mediates caffeine-induced impulsivity. A-B. Knockdown of dDA1 ( UAS-dDA1 RNAi ) in α/β ( MB008B ) or ψ ( MB009B ) neurons, but not in α’/β’ (MB005B) neurons, abolished caffeine-induced impulsivity (ANOVA with post hoc Dunnett, p < 0.0001; n = 10; different letters indicate statistically significant differences: purple bars, females; teal bars, males). C-D. Reinstatement of dDA1 in α/β ( NP3061,dumb 2 ) or ψ ( NP1131;dumb 2 ) neurons in dumb 2 restored caffeine-induced impulsivity while reinstatement in α’/β’ ( c305a;dumb 2 ) neurons did not (ANOVA with post hoc Tukey; ns, p > 0.05, **, p < 0.005, ***, p < 0.0001; n = 6-10). E-F. Overexpression of dDA1 in α’/β’ ( c305a and MB005B ) or α/β ( c739 and MB008B ) neurons resulted in caffeine-induced impulsivity comparable to control ( pBDP ), whereas overexpression in ψ ( NP1131 and MB009B ) neurons led to significantly higher impulsivity (ANOVA with post hoc Dunnett, ***, p < 0.0001; n = 10-11). To further test the lob-specific requirement of dDA1, we reinstated its expression in individual MB lobes in the dumb 2 mutant background 19 , 33 . Restoring dDA1 in γ lobes (NP1131) or α/β lobes (NP3061) fully rescued caffeine-induced impulsivity, whereas restoration in α’/β’ lobes (c305a) did not ( Figure 5C , female: ANOVA, p < 0.0001, n = 6–8; Figure 5D , male: ANOVA, p < 0.0001, n = 10). Interestingly, γ-lobe restoration led to even greater impulsivity than that observed in CS or in α/β-lobe rescue, suggesting heightened sensitivity of γ-lobe neurons to dDA1 activity. To test this directly, we overexpressed dDA1 in individual MB lobes in a wild-type background. Overexpression in γ lobes (NP1131 or MB009B) significantly enhanced caffeine-induced impulsivity relative to CS, whereas overexpression in α/β lobes (c739 or MB008B) or α’/β’ lobes (via c305a or MB005B) had no effect ( Figure 5E , female: ANOVA, p < 0.0001, n = 10–11; Figure 5F , male: ANOVA, p < 0.0001, n = 10). Together, these findings demonstrate that dDA1 in the α/β and γ lobes of the MB is essential for mediating caffeine-induced impulsivity, with the γ lobes exhibiting heightened sensitivity to dDA1 activity. Discussion In this report, we have shown that nighttime caffeine intake disrupts inhibitory control in Drosophila through dopamine D1 receptor (dDA1) signaling in the MB, revealing a neural and molecular framework by which caffeine modulates impulse control. Notably, this behavioral phenotype was not attributable to general hyperactivity, reinforcing its specificity to inhibitory control. These findings expand the behavioral repertoire influenced by caffeine beyond arousal and provide a mechanistic basis for its time-dependent effects on cognitive function. We show that caffeine impairs inhibitory control only when consumed at night, despite similar internal caffeine concentrations during day and night intake. This finding suggests a strong interaction between caffeine’s effects and temporal factors, likely involving circadian regulation. On the contrary, sleep deprivation alone, whether mechanical or light-induced, did not produce impulsivity, nor did it amplify caffeine’s effects. These results together suggest that caffeine-induced impulsivity is independent of generalized arousal or sleep loss, implicating a distinct, temporally gated mechanism. This chrono-dependent sensitivity parallels findings from human studies, where cognitive and behavioral responses to caffeine vary by circadian phase. For example, morning, but not evening, caffeine intake promotes performance enhancements, while evening caffeine intake delays melatonin rhythms and disrupts sleep architecture 20 – 22 . These findings underscore the significance of circadian context in shaping caffeine’s impact on behavior. Our work establishes that dopaminergic signaling is necessary and sufficient for caffeine’s effect on inhibitory control. Caffeine-induced impulsivity was abolished in flies with reduced dopamine biosynthesis or silenced PAM dopaminergic neurons, and conversely, it was amplified in flies with elevated extracellular dopamine. Targeted manipulations in MB further identified the dDA1 receptor in the α/β and γ lobes as critical for mediating this dopaminergic effect. Consistent with our findings, D1 receptor signaling in the prefrontal cortex is known to regulate impulse control in both rodents and humans, and caffeine has been shown to impair decision-making and promote risk-taking behavior 34 – 39 . Notably, high caffeine consumption in children, adolescents and young adults has been linked to greater sensation seeking and risk-taking tendencies 40 , 41 . In gamblers, caffeine use is associated with earlier onset of gambling, heightened impulsivity, and increased nicotine co-use 37 . Also in spontaneously hypertensive rats, an animal model of ADHD, chronic caffeine treatment corrects dopaminergic dysfunction and improves attention and working memory, supporting a functional link between caffeine and dopamine signaling in cognitive control 42 . Caffeine promotes wakefulness in rodents by antagonizing adenosine receptors and enhancing dopamine signaling 43 , 44 . In Drosophila , it enhances wakefulness independently of adenosine antagonism 25 but requires dopamine signaling. Specifically, caffeine acts presynaptically to enhance dopaminergic activity in PAM neurons 24 . Its wake-promoting effect is then mediated postsynaptically by dDA1 in the MB α/β and γ lobes 26 . Notably, our results suggest that the same neural circuitry also mediates caffeine-induced motor impulsivity independently of sleep loss. This MB substructures are also known to regulate multiple complex behaviors such as learning, memory, behavioral flexibility, and decision making 16 – 19 , 23 , 45 – 48 . Future research should explore how caffeine’s diverse effects are mediated by overlapping neurochemical pathways and neural structures. Our findings align with growing evidence that dopaminergic signaling is closely intertwined with circadian timing. Dopamine release follows daily rhythms, peaking during the active phase in both flies and rodents, and is itself regulated by, and contributes to, circadian clock function 49 , 50 . In Drosophila , light-dependent upregulation of dDA1 in specific circadian neurons promotes morning arousal, highlighting time-of-day-dependent dopamine sensitivity 50 . This relationship is reciprocal as dopamine modulates circadian gene expression and neuronal excitability, and its disruption contributes to disorders like Parkinson’s disease, which features both circadian and dopaminergic dysfunction 51 , 52 . Notably, PAM cluster dopamine neurons implicated in caffeine-induced impulsivity also show circadian variation in vulnerability to oxidative stress, which is abolished in clock gene mutants 53 . Together, these data suggest that caffeine acts on a circadian-gated dopaminergic system that regulates behavioral inhibition. Temporal sensitivity of dopamine signaling may underlie the time-specific effects of caffeine on impulsivity. Another novel aspect of our findings is the identification of sex differences in caffeine-induced impulsivity, with female flies displaying greater sensitivity than males. This mirrors human studies showing that females are more likely to experience negative caffeine-related effects such as anxiety and nervousness, whereas males more often report positive effects, like enhanced perception and vigor 54 , 55 . Similar sex-specific responses to caffeine have been seen in rodents 56 – 60 ; for example, regular intake of caffeinated coffee induces sex-dependent changes in mice, with females exhibiting increased dominance and self-care and male showing greater sociability 60 . Together, these findings underscore the complex, sex-dependent nature of caffeine’s behavioral effects. Our study provides a tractable model for uncovering the neural and molecular mechanisms underlying sex-specific sensitivity to caffeine, particularly in the context of impulsivity. In summary, our study shows that nighttime caffeine intake disrupts inhibitory control via D1 (dDA1) dopamine receptor signaling in the MB α/β and γ lobes, with effects that are independent of sleep deprivation and modulated by both sex and circadian phase. These findings advance our understanding of how executive function is influenced by caffeine and underscore Drosophila ’s utility for dissecting the neural basis of impulsivity. Importantly, we provide direct evidence that the behavioral impact of psychoactive substances, like caffeine, is time-of-day dependent, providing support to chronotherapy approaches and emphasizing the need to integrate circadian biology into behavioral neuroscience. Author contributions Conceptualization: EBS, PRS, KAH Methodology: EBS, PRS Investigation: EBS, PRS Visualization: EBS, PRS Supervision: KAH Writing—original draft: EBS, KAH Writing—review & editing: EBS, PRS, KAH Competing interests Authors declare that they have no competing interests. Data and materials availability All raw data and materials used in the study are available upon request from the corresponding authors. Footnote Erick B. Saldes current address: Department of Cancer Biology & Pharmacology, The University of Illinois College of Medicine Peoria, One Illini Dr. Peoria, IL 61615 STAR METHODS KEY RESOURCES TABLE View this table: View inline View popup RESOURCE AVAILABILITY Lead contact Any information, resource, and reagent requests should be directed to the lead contact, Kyung-An Han ( khan{at}utep.edu ). Materials availability This study did not generate new reagents and most fly strains used in the study are available from the Bloomington Drosophila Stock Center. The D1 receptor mutant alleles and UAS-dDA1 fly lines are available on request from the lead contact. Data and code availability All data reported in this study is available from the lead contact upon request. EXPERIMENTAL MODEL AND STUDY PARTICIPANT DETAILS In this study, we used Drosophila melanogaster as a model system. Specific information about fly strains, culture, and maintenance as well as specific experimental conditions are found in the subsequent sections below. METHOD DETAILS Fly strains and culture The wild-type strain used in this study is Canton-S ( CS ). We previously described fumin ( fmn ) 61 , dumb 1 19 , dumb 2 19 , dumb 4 31 , d2r 31 , and UAS-dDA1 19 – all of which were placed in the CS background. The following stocks were obtained from the Bloomington Drosophila stock center (Bloomington, IN): ple f01945 (noted as ple-1; 18492), ple MI02717 (noted as ple-2; 36034), UAS-TNT (28838), UAS-IMP-TNT (28839), UAS-dDA1 RNAi (31765), GMR58E02-GAL4 (41347), c305a-GAL4 (30829), MB005B-GAL4 (68306), MB008B-GAL4 (68291), and MB009B-GAL4 (68292); pBDP-GAL4 from Dr Anderson (California Institute of Technology, Pasadena, CA) and NP1131-GAL4 and NP3061-GAL4 from Dr. Dubnau (Stony Brook University School of Medicine, Stony Brook, NY). All Drosophila strains were raised on a standard cornmeal/sucrose/yeast/agar medium at 25° C with 50 % relative humidity under a 12 h light/12 h dark cycle. For experiments, female and male flies were collected under carbon dioxide within two days after eclosion and housed in same-sex groups of 13 per vial (representing n = 1). Both females and males were examined separately. Caffeine feeding Caffeine (Sigma-Aldrich, C0750) was mixed into melted standard fly food medium (cornmeal/sucrose/yeast/agar) at a concentration of 10 mg/mL for all experiments except for the dose-response analysis in Figure 1A and 1B , where additional concentrations of 1, 5 and 7.5 mg/mL were used 18 , 26 , 62 – 65 . For nighttime caffeine exposure, groups of 13 female or male flies (n = 1) were transferred to vials containing caffeine-laced food 30 min before lights-off and remained on this food throughout the dark cycle (ZT12–ZT24). Flies were immediately tested in the Go/No-Go assay at the end of the dark period. For the daytime feeding condition, flies were exposed to 10 mg/mL caffeine for 4 h (ZT0–ZT4) and tested immediately afterward. To confirm ingestion of the caffeine-containing food, green food dye (McCormick, 930647) was added to the mixture of fly food medium and caffeine, and consumption was verified by visual inspection of dye accumulation in the abdomen. Sleep Disruption Two distinct methods were used to disrupt sleep in Drosophila . For mechanical sleep deprivation (MSD), vials containing flies were placed on a vortexer and subjected to randomized shaking for 2 s within every 20-s interval throughout the dark cycle, as previously described 27 . For light-induced sleep disruption (LSD), lights were randomly turned on for 30 min once every hour during the dark phase, following established protocols 28 . Flies were immediately subjected to the Go/No-Go test at the end of the dark cycle to assess behavioral consequences of sleep disruption. Go/No-Go test The Go/No-Go test was performed as previously described 18 , 23 . Briefly, Flies were placed individually into a clear rectangular plexiglass chamber (60 mm L X 60 mm W X 15 mm H) connected to a filtered air source. After a 1-min acclimation period to explore the chamber, a continuous airflow of 10 L/min was applied for 10 min. Fly behavior was video recorded to monitor movements before and during airflow exposure. Videos were analyzed for flying events manually or using Viewer3 tracking software (BIObserve Technologies, Bonn, Germany), which enables automated tracking and quantification of individual fly movement speed in mm/sec. Raw data were exported to Excel (Microsoft, Redmond, WA). Movements exceeding 60 mm/sec were classified as loss of inhibition events (LIEs 18 , 23 ), which were scored per fly per min. Both total LIE or peak LIEs (maximum LIEs per minute) were used for comparison between control and experimental groups. Baseline locomotor activity during the initial no-airflow phase (“go” period) was assessed using average walking speed (reported in Figure 1E-F and Figure 3A-H ). All behavioral experiments were conducted with the experimenter blind to condition, sex, and genotype. Control and experimental groups were always tested within the same experimental session. Multiple independent groups of flies derived from separate seedings, or genetic crosses were used for all behavioral assays. Caffeine analysis Caffeine levels in flies were measured using a commercially available Caffeine ELISA kit (Catalog no. 515575; ABRAXIS, Warminster, PA, USA). For each feeding condition and sex, five whole flies were collected and transferred into an ice-cold KONTES Micro Tissue Grinder (ThermoFisher Scientific, Waltham, MA). Flies were homogenized in 50 μl of Sample Diluent flies for 30 – 45 s. The homogenate was then transferred to a clean microcentrifuge tube and centrifuged at 14,000 rpm for 10 min at 4° C. The resulting supernatant was used for caffeine quantification according to the manufacturer’s instructions. Three independent biological replicates (each from separate broods and feedings) were analyzed per treatment group and sex. QUANTIFICATION AND STATISTICAL ANALYSIS All statistical analyses were performed using either the Minitab software (Minitab, State College, PA) or JMP (SAS, Cary, NC). Raw data were analyzed using the Anderson–Darling goodness-of-fit test for distribution and are reported as mean + SEM. Normally distributed data were analyzed by either a two-tailed Student’s t -test for two groups or by ANOVA followed by post hoc Tukey’s multiple-comparison for three or more groups or Dunnett’s test to compare experimental groups with a control group. Non-normally distributed data were analyzed by Kruskal-Wallis and post hoc Mann-Whitney tests. Significant difference among the groups under comparison was determined using an α level of 0.05 in all analyses. Acknowledgments We are grateful to the Bloomington Stock Center and Drs. Dubnau and Anderson for sharing fly lines, the Cytometry, Screening, and Imaging Core at Border Biomedical Research Center on confocal microscopy. We are also thankful to the past and current lab members for their help, discussion, and support. This work was supported by the National Institutes of Health grant R21MH109953 (KAH), Brain & Behavior Research Foundation grant (KAH) and National Institutes of Health grant R16GM145548(KAH). National Institutes of Health grant R21MH109953 (KAH) Brain & Behavior Research Foundation grant (KAH) National Institutes of Health grant R16GM145548(KAH) Funder Information Declared NIH , R21MH109953 , R16GM145548 Brain & Behavior Research Foundation References 1. ↵ Fulgoni , V.L. , Keast , D.R. , and Lieberman , H.R. ( 2015 ). Trends in intake and sources of caffeine in the diets of US adults: 2001-2010 . Am J Clin Nutr 101 , 1081 – 1087 . doi: 10.3945/ajcn.113.080077 . OpenUrl Abstract / FREE Full Text 2. ↵ Walsh , J.K. , Muehlbach , M.J. , Humm , T.M. , Dickins , Q.S. , Sugerman , J.L. , and Schweitzer , P.K. ( 1990 ). Effect of caffeine on physiological sleep tendency and ability to sustain wakefulness at night . Psychopharmacology (Berl ) 101 , 271 – 273 . doi: 10.1007/BF02244139 . OpenUrl CrossRef PubMed 3. Muehlbach , M.J. , and Walsh , J.K. ( 1995 ). The effects of caffeine on simulated night-shift work and subsequent daytime sleep . Sleep 18 , 22 – 29 . doi: 10.1093/sleep/18.1.22 . OpenUrl CrossRef PubMed Web of Science 4. ↵ Lieberman , H.R. , Tharion , W.J. , Shukitt-Hale , B. , Speckman , K.L. , and Tulley , R. ( 2002 ). Effects of caffeine, sleep loss, and stress on cognitive performance and mood during US Navy SEAL training . Psychopharmacology 164 , 250 – 261 . OpenUrl CrossRef PubMed 5. Franke , A.G. , Bagusat , C. , McFarlane , C. , Tassone-Steiger , T. , Kneist , W. , and Lieb , K. ( 2015 ). The Use of Caffeinated Substances by Surgeons for Cognitive Enhancement . Ann Surg 261 , 1091 – 1095 . doi: 10.1097/SLA.0000000000000830 . OpenUrl CrossRef PubMed 6. Ogeil , R.P. , Barger , L.K. , Lockley , S.W. , O’Brien , C.S. , Sullivan , J.P. , Qadri , S. , Lubman , D.I. , Czeisler , C.A. , and Rajaratnam , S.M.W. ( 2018 ). Cross-sectional analysis of sleep-promoting and wake-promoting drug use on health, fatigue-related error, and near-crashes in police officers . BMJ Open 8 , e022041 . doi: 10.1136/bmjopen-2018-022041 . OpenUrl Abstract / FREE Full Text 7. Irwin , C. , Khalesi , S. , Desbrow , B. , and McCartney , D. ( 2020 ). Effects of acute caffeine consumption following sleep loss on cognitive, physical, occupational and driving performance: A systematic review and meta-analysis . Neurosci Biobehav Rev 108 , 877 – 888 . doi: 10.1016/j.neubiorev.2019.12.008 . OpenUrl CrossRef PubMed 8. ↵ Bonnet , M.H. , and Arand , D.L. ( 1994 ). Impact of naps and caffeine on extended nocturnal performance . Physiol Behav 56 , 103 – 109 . doi: 10.1016/0031-9384(94)90266-6 . OpenUrl CrossRef PubMed 9. ↵ Kamimori , G.H. , McLellan , T.M. , Tate , C.M. , Voss , D.M. , Niro , P. , and Lieberman , H.R. ( 2015 ). Caffeine improves reaction time, vigilance and logical reasoning during extended periods with restricted opportunities for sleep . Psychopharmacology (Berl ) 232 , 2031 – 2042 . doi: 10.1007/s00213-014-3834-5 . OpenUrl CrossRef 10. Wingelaar-Jagt , Y.Q. , Bottenheft , C. , Riedel , W.J. , and Ramaekers , J.G. ( 2023 ). Effects of modafinil and caffeine on night-time vigilance of air force crewmembers: A randomized controlled trial . J Psychopharmacol 37 , 172 – 180 . doi: 10.1177/02698811221142568 . OpenUrl CrossRef PubMed 11. Killgore , W.D. , Kamimori , G.H. , and Balkin , T.J. ( 2014 ). Caffeine improves the efficiency of planning and sequencing abilities during sleep deprivation . J Clin Psychopharmacol 34 , 660 – 662 . doi: 10.1097/JCP.0000000000000184 . OpenUrl CrossRef PubMed 12. ↵ Huffmyer , J.L. , Kleiman , A.M. , Moncrief , M. , Scalzo , D.C. , Cox , D.J. , and Nemergut , E.C. ( 2020 ). Impact of Caffeine Ingestion on the Driving Performance of Anesthesiology Residents After 6 Consecutive Overnight Work Shifts . Anesth Analg 130 , 66 – 75 . doi: 10.1213/ANE.0000000000004252 . OpenUrl CrossRef PubMed 13. ↵ Daly , J.W. , and Fredholm , B.B. ( 1998 ). Caffeine—an atypical drug of dependence . Drug and alcohol dependence 51 , 199 – 206 . OpenUrl CrossRef PubMed Web of Science 14. Parry , D. , Iqbal , S. , Harrap , I. , Oeppen , R.S. , and Brennan , P.A. ( 2023 ). Caffeine: benefits and drawbacks for technical performance . Br J Oral Maxillofac Surg 61 , 198 – 201 . doi: 10.1016/j.bjoms.2023.01.007 . OpenUrl CrossRef PubMed 15. ↵ Jacobson , B.H. , Winter-Roberts , K. , and Gemmell , H.A. ( 1991 ). Influence of caffeine on selected manual manipulation skills . Percept Mot Skills 72 , 1175 – 1181 . doi: 10.2466/pms.1991.72.3c.1175 . OpenUrl CrossRef PubMed 16. ↵ Cohn , R. , Morantte , I. , and Ruta , V. ( 2015 ). Coordinated and Compartmentalized Neuromodulation Shapes Sensory Processing in Drosophila . Cell 163 , 1742 – 1755 . doi: 10.1016/j.cell.2015.11.019 . OpenUrl CrossRef PubMed 17. Modi , M.N. , Rajagopalan , A.E. , Rouault , H. , Aso , Y. , and Turner , G.C. ( 2023 ). Flexible specificity of memory in . Elife 12 . doi: 10.7554/eLife.80923 . OpenUrl CrossRef PubMed 18. ↵ Sabandal , P.R. , Kim , Y.C. , Sabandal , J.M. , and Han , K.A. ( 2025 ). Social context and dopamine signaling converge in the mushroom body to drive impulsivity . bioRxiv . doi: 10.1101/2025.02.21.639508 . OpenUrl Abstract / FREE Full Text 19. ↵ Kim , Y.C. , Lee , H.G. , and Han , K.A. ( 2007 ). D1 dopamine receptor dDA1 is required in the mushroom body neurons for aversive and appetitive learning in Drosophila . J Neurosci 27 , 7640 – 7647 . doi: 10.1523/JNEUROSCI.1167-07.2007 . OpenUrl Abstract / FREE Full Text 20. ↵ Stojanović , E. , Scanlan , A.T. , Milanović , Z. , Fox , J.L. , Stanković , R. , and Dalbo , V.J. ( 2022 ). Acute caffeine supplementation improves jumping, sprinting, and change-of-direction performance in basketball players when ingested in the morning but not evening . Eur J Sport Sci 22 , 360 – 370 . doi: 10.1080/17461391.2021.1874059 . OpenUrl CrossRef PubMed 21. Zhang , Y. , Yang , W. , Xue , Y. , Hou , D. , Chen , S. , Xu , Z. , Peng , S. , Zhao , H. , Wang , C. , and Liu , C. ( 2024 ). Timing Matters: Time of Day Impacts the Ergogenic Effects of Caffeine-A Narrative Review . Nutrients 16 . doi: 10.3390/nu16101421 . OpenUrl CrossRef 22. ↵ Burke , T.M. , Markwald , R.R. , McHill , A.W. , Chinoy , E.D. , Snider , J.A. , Bessman , S.C. , Jung , C.M. , O’Neill , J.S. , and Wright , K.P. ( 2015 ). Effects of caffeine on the human circadian clock in vivo and in vitro . Sci Transl Med 7 , 305ra146 . doi: 10.1126/scitranslmed.aac5125 . OpenUrl Abstract / FREE Full Text 23. ↵ Sabandal , P.R. , Saldes , E.B. , and Han , K.A. ( 2022 ). Acetylcholine deficit causes dysfunctional inhibitory control in an aging-dependent manner . Sci Rep 12 , 20903 . doi: 10.1038/s41598-022-25402-z . OpenUrl CrossRef 24. ↵ Nall , A.H. , Shakhmantsir , I. , Cichewicz , K. , Birman , S. , Hirsh , J. , and Sehgal , A. ( 2016 ). Caffeine promotes wakefulness via dopamine signaling in Drosophila . Sci Rep 6 , 20938 . doi: 10.1038/srep20938 . OpenUrl CrossRef PubMed 25. ↵ Wu , M.N. , Ho , K. , Crocker , A. , Yue , Z. , Koh , K. , and Sehgal , A. ( 2009 ). The effects of caffeine on sleep in Drosophila require PKA activity, but not the adenosine receptor . J Neurosci 29 , 11029 – 11037 . doi: 10.1523/JNEUROSCI.1653-09.2009 . OpenUrl Abstract / FREE Full Text 26. ↵ Andretic , R. , Kim , Y.C. , Jones , F.S. , Han , K.A. , and Greenspan , R.J. ( 2008 ). Drosophila D1 dopamine receptor mediates caffeine-induced arousal . Proc Natl Acad Sci U S A 105 , 20392 – 20397 . doi: 10.1073/pnas.0806776105 . OpenUrl Abstract / FREE Full Text 27. ↵ Kayser , M.S. , Mainwaring , B. , Yue , Z. , and Sehgal , A. ( 2015 ). Sleep deprivation suppresses aggression in Drosophila . Elife 4 , e07643 . doi: 10.7554/eLife.07643 . OpenUrl CrossRef PubMed 28. ↵ Williams , M.J. , Perland , E. , Eriksson , M.M. , Carlsson , J. , Erlandsson , D. , Laan , L. , Mahebali , T. , Potter , E. , Frediksson , R. , Benedict , C. , and Schiöth , H.B. ( 2016 ). Recurrent Sleep Fragmentation Induces Insulin and Neuroprotective Mechanisms in Middle-Aged Flies . Front Aging Neurosci 8 , 180 . doi: 10.3389/fnagi.2016.00180 . OpenUrl CrossRef PubMed 29. ↵ Silva , B. , Hidalgo , S. , and Campusano , J.M. ( 2020 ). Dop1R1, a type 1 dopaminergic receptor expressed in Mushroom Bodies, modulates Drosophila larval locomotion . PLoS One 15 , e0229671 . doi: 10.1371/journal.pone.0229671 . OpenUrl CrossRef PubMed 30. ↵ Makos , M.A. , Han , K.A. , Heien , M.L. , and Ewing , A.G. ( 2010 ). Using In Vivo Electrochemistry to Study the Physiological Effects of Cocaine and Other Stimulants on the Drosophila melanogaster Dopamine Transporter . ACS Chem Neurosci 1 , 74 – 83 . doi: 10.1021/cn900017w . OpenUrl CrossRef PubMed 31. ↵ Lim , J. , Fernandez , A.I. , Hinojos , S.J. , Aranda , G.P. , James , J. , Seong , C.S. , and Han , K.A. ( 2018 ). The mushroom body D1 dopamine receptor controls innate courtship drive . Genes Brain Behav 17 , 158 – 167 . doi: 10.1111/gbb.12425 . OpenUrl CrossRef PubMed 32. ↵ Kim , Y.C. , Lee , H.G. , Seong , C.S. , and Han , K.A. ( 2003 ). Expression of a D1 dopamine receptor dDA1/DmDOP1 in the central nervous system of Drosophila melanogaster . Gene Expr Patterns 3 , 237 – 245 . doi: 10.1016/s1567-133x(02)00098-4 . OpenUrl CrossRef PubMed Web of Science 33. ↵ Qin , H. , Cressy , M. , Li , W. , Coravos , J.S. , Izzi , S.A. , and Dubnau , J. ( 2012 ). Gamma neurons mediate dopaminergic input during aversive olfactory memory formation in Drosophila . Curr Biol 22 , 608 – 614 . doi: 10.1016/j.cub.2012.02.014 . OpenUrl CrossRef PubMed 34. ↵ Arnsten , A.F. , and Pliszka , S.R. ( 2011 ). Catecholamine influences on prefrontal cortical function: relevance to treatment of attention deficit/hyperactivity disorder and related disorders . Pharmacol Biochem Behav 99 , 211 – 216 . doi: 10.1016/j.pbb.2011.01.020 . OpenUrl CrossRef PubMed 35. Lone , S.R. , Potdar , S. , Srivastava , M. , and Sharma , V.K. ( 2016 ). Social Experience Is Sufficient to Modulate Sleep Need of Drosophila without Increasing Wakefulness . PLoS One 11 , e0150596 . doi: 10.1371/journal.pone.0150596 . OpenUrl CrossRef PubMed 36. Cheng , R.K. , and Liao , R.M. ( 2017 ). Regional differences in dopamine receptor blockade affect timing impulsivity that is altered by d-amphetamine on differential reinforcement of low-rate responding (DRL) behavior in rats . Behav Brain Res 331 , 177 – 187 . doi: 10.1016/j.bbr.2017.05.020 . OpenUrl CrossRef PubMed 37. ↵ Grant , J.E. , and Chamberlain , S.R. ( 2018 ). Caffeine’s influence on gambling behavior and other types of impulsivity . Addict Behav 76 , 156 – 160 . doi: 10.1016/j.addbeh.2017.08.007 . OpenUrl CrossRef PubMed 38. Smith , A. ( 2002 ). Effects of caffeine on human behavior . Food Chem Toxicol 40 , 1243 – 1255 . doi: 10.1016/s0278-6915(02)00096-0 . OpenUrl CrossRef PubMed Web of Science 39. ↵ Vijayraghavan , S. , Major , A.J. , and Everling , S. ( 2016 ). Dopamine D1 and D2 Receptors Make Dissociable Contributions to Dorsolateral Prefrontal Cortical Regulation of Rule-Guided Oculomotor Behavior . Cell Rep 16 , 805 – 816 . doi: 10.1016/j.celrep.2016.06.031 . OpenUrl CrossRef PubMed 40. ↵ Temple , J.L. , Ziegler , A.M. , Graczyk , A.M. , and Crandall , A. ( 2017 ). Effects of acute and chronic caffeine on risk-taking behavior in children and adolescents . J Psychopharmacol 31 , 561 – 568 . doi: 10.1177/0269881117691568 . OpenUrl CrossRef PubMed 41. ↵ Arria , A.M. , Caldeira , K.M. , Kasperski , S.J. , Vincent , K.B. , Griffiths , R.R. , and O’Grady , K.E. ( 2011 ). Energy drink consumption and increased risk for alcohol dependence . Alcohol Clin Exp Res 35 , 365 – 375 . doi: 10.1111/j.1530-0277.2010.01352.x . OpenUrl CrossRef PubMed Web of Science 42. ↵ Pandolfo , P. , Machado , N.J. , Köfalvi , A. , Takahashi , R.N. , and Cunha , R.A. ( 2013 ). Caffeine regulates frontocorticostriatal dopamine transporter density and improves attention and cognitive deficits in an animal model of attention deficit hyperactivity disorder . Eur Neuropsychopharmacol 23 , 317 – 328 . doi: 10.1016/j.euroneuro.2012.04.011 . OpenUrl CrossRef PubMed 43. ↵ Lazarus , M. , Shen , H.Y. , Cherasse , Y. , Qu , W.M. , Huang , Z.L. , Bass , C.E. , Winsky-Sommerer , R. , Semba , K. , Fredholm , B.B. , Boison , D. , et al. ( 2011 ). Arousal effect of caffeine depends on adenosine A2A receptors in the shell of the nucleus accumbens . J Neurosci 31 , 10067 – 10075 . doi: 10.1523/JNEUROSCI.6730-10.2011 . OpenUrl Abstract / FREE Full Text 44. ↵ Oishi , Y. , and Lazarus , M. ( 2017 ). The control of sleep and wakefulness by mesolimbic dopamine systems . Neurosci Res 118 , 66 – 73 . doi: 10.1016/j.neures.2017.04.008 . OpenUrl CrossRef PubMed 45. ↵ Guven-Ozkan , T. , and Davis , R.L. ( 2014 ). Functional neuroanatomy of Drosophila olfactory memory formation . Learn Mem 21 , 519 – 526 . doi: 10.1101/lm.034363.114 . OpenUrl Abstract / FREE Full Text 46. de Belle , J.S. , and Heisenberg , M. ( 1994 ). Associative odor learning in Drosophila abolished by chemical ablation of mushroom bodies . Science 263 , 692 – 695 . doi: 10.1126/science.8303280 . OpenUrl Abstract / FREE Full Text 47. Martin , J.R. , Ernst , R. , and Heisenberg , M. ( 1998 ). Mushroom bodies suppress locomotor activity in Drosophila melanogaster . Learn Mem 5 , 179 – 191 . OpenUrl Abstract / FREE Full Text 48. ↵ Pitman , J.L. , McGill , J.J. , Keegan , K.P. , and Allada , R. ( 2006 ). A dynamic role for the mushroom bodies in promoting sleep in Drosophila . Nature 441 , 753 – 756 . doi: 10.1038/nature04739 . OpenUrl CrossRef PubMed Web of Science 49. ↵ Korshunov , K.S. , Blakemore , L.J. , and Trombley , P.Q. ( 2017 ). Dopamine: A Modulator of Circadian Rhythms in the Central Nervous System . Front Cell Neurosci 11 , 91 . doi: 10.3389/fncel.2017.00091 . OpenUrl CrossRef PubMed 50. ↵ Le , J.Q. , Ma , D. , Dai , X. , and Rosbash , M. ( 2024 ). Light and dopamine impact two circadian neurons to promote morning wakefulness . Curr Biol 34 , 3941 – 3954 .e3944. doi: 10.1016/j.cub.2024.07.056 . OpenUrl CrossRef PubMed 51. ↵ Radwan , B. , Liu , H. , and Chaudhury , D. ( 2019 ). The role of dopamine in mood disorders and the associated changes in circadian rhythms and sleep-wake cycle . Brain Res 1713 , 42 – 51 . doi: 10.1016/j.brainres.2018.11.031 . OpenUrl CrossRef PubMed 52. ↵ Xu , K. , Zhang , Y. , Shi , Y. , Zhang , C. , Wang , T. , Lv , P. , Bai , Y. , and Wang , S. ( 2024 ). Circadian rhythm disruption: a potential trigger in Parkinson’s disease pathogenesis . Front Cell Neurosci 18 , 1464595 . doi: 10.3389/fncel.2024.1464595 . OpenUrl CrossRef PubMed 53. ↵ Majcin Dorcikova , M. , Duret , L.C. , Pottié , E. , and Nagoshi , E. ( 2023 ). Circadian clock disruption promotes the degeneration of dopaminergic neurons in male Drosophila . Nat Commun 14 , 5908 . doi: 10.1038/s41467-023-41540-y . OpenUrl CrossRef PubMed 54. ↵ Domaszewski , P. ( 2023 ). Gender Differences in the Frequency of Positive and Negative Effects after Acute Caffeine Consumption . Nutrients 15 . doi: 10.3390/nu15061318 . OpenUrl CrossRef 55. ↵ Temple , J.L. , Bulkley , A.M. , Briatico , L. , and Dewey , A.M. ( 2009 ). Sex differences in reinforcing value of caffeinated beverages in adolescents . Behav Pharmacol 20 , 731 – 741 . doi: 10.1097/FBP.0b013e328333b27c . OpenUrl CrossRef PubMed Web of Science 56. ↵ Boyer , M. , Rees , S. , Quinn , J. , Grattan-Miscio , K. , McCallum , M. , and Saari , M.J. ( 2003 ). Caffeine as a performance-enhancing drug in rats: sex, dose, housing, and task considerations . Percept Mot Skills 97 , 259 – 270 . doi: 10.2466/pms.2003.97.1.259 . OpenUrl CrossRef PubMed 57. Hughes , R.N. , and Hancock , N.J. ( 2017 ). Effects of acute caffeine on anxiety-related behavior in rats chronically exposed to the drug, with some evidence of possible withdrawal-reversal . Behav Brain Res 321 , 87 – 98 . doi: 10.1016/j.bbr.2016.12.019 . OpenUrl CrossRef PubMed 58. Turgeon , S.M. , Townsend , S.E. , Dixon , R.S. , Hickman , E.T. , and Lee , S.M. ( 2016 ). Chronic caffeine produces sexually dimorphic effects on amphetamine-induced behavior, anxiety and depressive-like behavior in adolescent rats . Pharmacol Biochem Behav 143 , 26 – 33 . doi: 10.1016/j.pbb.2016.01.012 . OpenUrl CrossRef PubMed 59. Hughes , R.N. , and Hancock , N.J. ( 2016 ). Strain-dependent effects of acute caffeine on anxiety-related behavior in PVG/c, Long-Evans and Wistar rats . Pharmacol Biochem Behav 140 , 51 – 61 . doi: 10.1016/j.pbb.2015.11.005 . OpenUrl CrossRef PubMed 60. ↵ Machado , N.J. , Ardais , A.P. , Nunes , A. , Szabó , E.C. , Silveirinha , V. , Silva , H.B. , Kaster , M.P. , and Cunha , R.A. ( 2024 ). Impact of Coffee Intake on Measures of Wellbeing in Mice . Nutrients 16 . doi: 10.3390/nu16172920 . OpenUrl CrossRef 61. ↵ Murillo Gonzalez , D.J. , Hernandez Granados , B.A. , Sabandal , P.R. , and Han , K.A. ( 2024 ). Social setting interacts with hyper dopamine to boost the stimulant effect of ethanol . Addict Biol 29 , e13420 . doi: 10.1111/adb.13420 . OpenUrl CrossRef PubMed 62. ↵ Shaw , P.J. , Cirelli , C. , Greenspan , R.J. , and Tononi , G. ( 2000 ). Correlates of sleep and waking in Drosophila melanogaster . Science 287 , 1834 – 1837 . doi: 10.1126/science.287.5459.1834 . OpenUrl Abstract / FREE Full Text 63. Hendricks , J.C. , Finn , S.M. , Panckeri , K.A. , Chavkin , J. , Williams , J.A. , Sehgal , A. , and Pack , A.I. ( 2000 ). Rest in Drosophila is a sleep-like state . Neuron 25 , 129 – 138 . doi: 10.1016/s0896-6273(00)80877-6 . OpenUrl CrossRef PubMed Web of Science 64. Lin , F.J. , Pierce , M.M. , Sehgal , A. , Wu , T. , Skipper , D.C. , and Chabba , R. ( 2010 ). Effect of taurine and caffeine on sleep-wake activity in Drosophila melanogaster . Nat Sci Sleep 2 , 221 – 231 . doi: 10.2147/NSS.S13034 . OpenUrl CrossRef PubMed 65. ↵ Inan , O.T. , Marcu , O. , Sanchez , M.E. , Bhattacharya , S. , and Kovacs , G.T. ( 2011 ). A portable system for monitoring the behavioral activity of Drosophila . J Neurosci Methods 202 , 45 – 52 . doi: 10.1016/j.jneumeth.2011.08.039 . OpenUrl CrossRef PubMed Web of Science Back to top Previous Next Posted June 13, 2025. Download PDF Email Thank you for your interest in spreading the word about bioRxiv. NOTE: Your email address is requested solely to identify you as the sender of this article. Your Email * Your Name * Send To * Enter multiple addresses on separate lines or separate them with commas. You are going to email the following Nighttime Caffeine Intake Increases Motor Impulsivity Message Subject (Your Name) has forwarded a page to you from bioRxiv Message Body (Your Name) thought you would like to see this page from the bioRxiv website. Your Personal Message CAPTCHA This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. Share Nighttime Caffeine Intake Increases Motor Impulsivity Erick Benjamin Saldes , Paul Rafael Sabandal , Kyung-An Han bioRxiv 2025.06.09.658656; doi: https://doi.org/10.1101/2025.06.09.658656 Share This Article: Copy Citation Tools Nighttime Caffeine Intake Increases Motor Impulsivity Erick Benjamin Saldes , Paul Rafael Sabandal , Kyung-An Han bioRxiv 2025.06.09.658656; doi: https://doi.org/10.1101/2025.06.09.658656 Citation Manager Formats BibTeX Bookends EasyBib EndNote (tagged) EndNote 8 (xml) Medlars Mendeley Papers RefWorks Tagged Ref Manager RIS Zotero Tweet Widget Facebook Like Google Plus One Subject Area Animal Behavior and Cognition Subject Areas All Articles Animal Behavior and Cognition (7792) Biochemistry (18186) Bioengineering (14359) Bioinformatics (43059) Biophysics (21938) Cancer Biology (19079) Cell Biology (26142) Clinical Trials (138) Developmental Biology (13637) Ecology (20367) Epidemiology (2067) Evolutionary Biology (24830) Genetics (15833) Genomics (22957) Immunology (18184) Microbiology (41303) Molecular Biology (17514) Neuroscience (90725) Paleontology (679) Pathology (2903) Pharmacology and Toxicology (4941) Physiology (7868) Plant Biology (15481) Scientific Communication and Education (2065) Synthetic Biology (4425) Systems Biology (9998) Zoology (2314) (function(){function c(){var b=a.contentDocument||a.contentWindow.document;if(b){var d=b.createElement('script');d.innerHTML="window.__CF$cv$params={r:'a1b4bc75b9ebfbb0',t:'MTc4NDA3NjI0MA=='};var a=document.createElement('script');a.src='/cdn-cgi/challenge-platform/scripts/jsd/main.js';document.getElementsByTagName('head')[0].appendChild(a);";b.getElementsByTagName('head')[0].appendChild(d)}}if(document.body){var a=document.createElement('iframe');a.height=1;a.width=1;a.style.position='absolute';a.style.top=0;a.style.left=0;a.style.border='none';a.style.visibility='hidden';document.body.appendChild(a);if('loading'!==document.readyState)c();else if(window.addEventListener)document.addEventListener('DOMContentLoaded',c);else{var e=document.onreadystatechange||function(){};document.onreadystatechange=function(b){e(b);'loading'!==document.readyState&&(document.onreadystatechange=e,c())}}}})();