Regarding associations with poor mental and physical health, the positive association with days of poor mental functioning suggests that sleep may be an important indicator of psychiatric disorders. Indeed, much of the literature in this domain focuses on specific sleep disorders and mental health risks including obstructive sleep apnea (69), insomnia (70), and symptoms of daytime sleepiness (71–73). However, habitual sleep, without the presence of a sleep disorder, seems to play an important role. Previous studies have demonstrated the role of sleep duration and psychological health risk, but most have focused on specific populations including the military (74, 75). Less is known, however, about the role of physical health functioning and sleep duration.