Sleep on It: Effects of Daytime Naps and Nighttime Sleep on Emotional Processing in College Students

Although many cultures have long practiced habitual daytime napping, its effects on cognitive and emotional functioning have only recently been the subject of scientific research. While the association of nighttime sleep duration and quality with affective functioning is quite well-established, previous napping studies have mainly focused on the napping effects on recently acquired skills or knowledge. Using validated experimental tasks, we propose to investigate the effects of daytime napping on three emotional processing functions: emotional memory, emotional reactivity, and inhibitory control in the affective domain in college students with either normal or chronically/habitually restricted sleep. Our main hypotheses are: (1) that the group with a nap opportunity compared to the group without will show: a) better recognition memory of emotional stimuli; b) reduced reactivity to stimuli of negative valence; and c) better inhibitory control; (2) that the benefits of napping on emotional processing will be associated with sleep architecture/ electroencephalographic (EEG) features such as the duration and latency of rapid eye movement (REM) sleep during the nap, sleep spindles, and slow wave density; and (3) that the benefits of napping will be greater in the habitually sleep-restricted group than in the group with normal sleep durations. In addition, we will explore the potential effects of pre-existing sleep quality on nap EEG architecture and the possible association of nap architecture with post-experiment nighttime sleep. We plan to test 80 college students who report habitual sleep restriction and 80 with normal sleep duration. The participants will be randomly assigned to either the Nap or Wake condition. All participants will complete measures of their baseline mood, sleep and nap patterns, perception of the effects of naps, and general intellectual functioning on Day 1. Participants will return on Day 6 for tests of affective and cognitive functions before and after the Nap/Wake condition. Participants’ naps will be monitored by polysomnography and their baseline sleep-wake patterns will be monitored using actigraphy and sleep diaries during baseline and experimental days of the study. Results of the study will provide novel information about the role of daytime naps and their electrophysiological features in emotional processing and their interaction with baseline sleep patterns. This new information will help inform decisions about the use of strategic napping to improve daytime emotional functioning and to compensate for inadequate nighttime sleep for college students and other populations with sleep and/or emotional problems.

Funding Source: RGC - General Research Fund (GRF)