Winding down for sleep: How behavioral, cognitive, motivational, and emotional factors interact to influence sleep regulation and health.

Animals do not simply fall asleep when they need rest. Without conscious effort, most animals engage in a series of sleep-preparatory behaviors, such as nesting. These are stereotypical actions performed in a temporally structured pre-sleep phase. Researchers have examined these behaviors from an evolutionary perspective, as they must provide some advantage. One hypothesis is that they have an indirect fitness benefit by facilitating de-arousal, making it easier to transition from wakefulness to sleep. In humans, regular positive bedtime routines are considered a main pediatric dimension of sleep health. In adults, difficulty in de-arousal at bedtime is a major issue for people with insomnia. Cognitive models of insomnia stress the strict association between arousal and cognitive-emotional factors driving behaviors. However, there is a lack of a unified framework to address the interplay between pre-sleep behaviors, psychological processes, and arousal levels in promoting or inhibiting evening winding down and wake-to-sleep transition. This narrative review aims to explore the role of behavioral components of sleep regulation, by focusing on the dynamical association between pre-sleep behaviors, cognitions, motivations, emotions, and arousal in relation to sleep health. We propose a framework to understand and investigate winding down behaviors as part of sleep regulation in humans.