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.