The present study aimed to reveal positive relationships between reduced sleepiness, subjective well-being, and pro-environmental behavior (switching off lights when not in use). A mailed questionnaire survey was used to collect data from randomly sampled residents (n = 324) in Tsukuba City to compare behavior and psychological factors as a function of sleepiness level. Respondents in the low sleepiness group were found to be engaged in more frequent pro-environmental behaviors compared to those in the high sleepiness group (4.9 ± 0.85 vs. 4.7 ± 0.96; t (322) = 1.85, p < 0.05). In addition, sleepiness was significantly correlated with subjective well-being (r = -0.13, p < 0.05) and pro-environmental behavior (r = -0.10, p < 0.05). The present study is the first to identify associations of sleepiness with pro-environmental behavior and subjective well-being. Reducing sleepiness could be an important factor to facilitate subjective well-being and engagement in pro-environmental behaviors.
