Increased sleep predicts annual decreases in psychological distress: Results from a six-year longitudinal panel sample

Objective: To investigate the annual temporal ordering of sleep quantity and psychological distress, separating between-person stability from within-person change. Design: Random-intercepts cross-lagged panel model using six annual waves of longitudinal data from the New Zealand Attitudes Values Study postal questionnaire.Participants: New Zealand Attitudes Values Study respondents in 2013, 2014, 2015, 2016, 2017, and 2018 (Ns = 17,890; 15,757; 13,904; 21,849; 17,031; and 47,462).Measurements: Participants were asked, “During the past month, on average, how many hours of actual sleep did you get per night?” and responded to the K6 psychological distress scale each year. They also reported their demographic characteristics. Results: Identified longitudinal associations between sleep duration and psychological distress in a traditional cross-lagged panel model were mostly attributable to the stability of the between-person differences in sleep duration and psychological distress. We provide evidence to suggest that increased sleep duration as indicated over a short period of time (i.e., one month) predicted lower within-person levels of psychological distress the following year. Psychological distress did not predict sleep duration, in contrast. Conclusions: Our analyses suggest that sleep duration in this sample of New Zealanders precedes psychological distress. This is significant given the propensity for short sleep in this sample and issues of poor mental health and short sleep among low SES indigenous members of this community. The promotion of adequate sleep duration may yield positive gains in psychological well-being.