0161 The Nap Trap: How Sleep Reactivity Influences Post-Nap Sleepiness

Abstract Introduction Sleep reactivity describes how vulnerable an individual’s sleep is to disturbances such as stress and other stimuli. Those with high sleep reactivity are more likely to have poorer sleep quality, especially in night shift workers who frequently experience environmental disruptions when sleeping during the day. However, the effect of sleep reactivity on sleep without the presence of environmental disruption has not been well established. Here, we assessed the extent to which sleep reactivity predicted how restorative a nap was. We predicted individuals with higher sleep reactivity would experience less restorative sleep as index by higher subjective sleepiness. Methods We collected data from night shift workers (N = 129) who had been in the lab for at least one period of 24 hours of saliva collection to participate in other studies. During their time in the lab participants sat in a dimly lit room with minimal outside noise. Sleep reactivity was evaluated using the Ford Insomnia Stress Test (FIRST) questionnaire, and sleepiness pre- vs post-nap was evaluated using Karolinska Sleepiness Scale (KSS). Participants' first naps in the lab were used to collect data, to control the effects of sleep inertia. Results We found that higher sleep reactivity was associated with a smaller decrease in pre- vs post- KSS scores (p = 0.017, β = 0.21, R² = 0.046). Conclusion Based on the results collected, there was significant evidence to support the original hypothesis. Sleep reactivity was positively associated with KSS score differences. Additionally, this data is the first to show that sleep reactivity limits how restorative sleep may be. This is likely because sleep reactivity makes individuals more easily aroused, thus reducing how restorative sleep is. However, based on the standardized coefficient and multiple r-squared, this is a small effect. Although sleep reactivity may not account for much sleepiness after sleep, these data suggest that even for night shift workers who get an equal amount of sleep, sleep reactivity may predict whose sleep is more restorative. Support (if any)