An Exploratory Study to Detect the Effects of the Combined Intake of Gamma-aminobutyric Acid (GABA) and L-theanine on Sleep by Wearable Device

Objectives Sleep disorders are a global issue, and supplements for sleep and new devices for daily sleep status assessment are becoming widely available. Gamma-aminobutyric acid (GABA) and L-theanine are commonly used dietary supplements to improve sleep. This study examined whether the combined GABA (700 mg/day) and L-theanine (200 mg/day) intake improve sleep in adults with sleep problems and whether the Fitbit Charge 5 can detect sleep status changes the supplements induced. Methods Participants received the supplements for four weeks, and changes in sleep quality measured using the Pittsburgh Sleep Quality Index (PSQI) and sleep-related data measured by the Fitbit Charge 5 were evaluated before and after the intake of the supplements. Results Results: obtained from 19 participants indicated significant improvement in the total PSQI score (9.42 ± 1.80 to 6.26 ± 1.66 (mean ± standard deviation), p<0.001). Sleep score improvement was insignificant for the Fitbit data(N=17). However, sleep recovery scores improved significantly (p=0.042). In addition, heart rate during sleep decreased with a significant difference of 1.3 bpm decrease in the first week of intake (p = 0.045). Conclusions The simultaneous intake of GABA and L-theanine improved sleep in adults, and the Fitbit Charge 5 could detect improvements in objective information regarding sleep status.