Napping and circadian sleep–wake regulation during healthy aging

Abstract

Study Objectives Daytime napping is frequently reported among the older population and has attracted increasing attention due to its association with multiple health conditions. Here, we tested whether napping in the aged is associated with altered circadian regulation of sleep, sleepiness, and vigilance performance. Methods Sixty healthy older individuals (mean age: 69 years, 39 women) were recruited with respect to their napping habits (30 nappers, 30 non-nappers). All participants underwent an in-lab 40-hour multiple nap protocol (10 cycles of 80 minutes of sleep opportunity alternating with 160 minutes of wakefulness), preceded and followed by a baseline and recovery sleep period. Saliva samples for melatonin assessment, sleepiness, and vigilance performance were collected during wakefulness and electrophysiological data were recorded to derive sleep parameters during scheduled sleep opportunities. Results The circadian amplitude of melatonin secretion was reduced in nappers, compared to non-nappers. Furthermore, nappers were characterized by higher sleep efficiencies and REM sleep proportion during day- compared to nighttime naps. The nap group also presented altered modulation in sleepiness and vigilance performance at specific circadian phases. Discussion Our data indicate that napping is associated with an altered circadian sleep–wake propensity rhythm. They thereby contribute to the understanding of the biological correlates underlying napping and/or sleep–wake cycle fragmentation during healthy aging. Altered circadian sleep–wake promotion can lead to a less distinct allocation of sleep into nighttime and/or a reduced wakefulness drive during the day, thereby potentially triggering the need to sleep at adverse circadian phase.

Inverted U-shaped relationship between sleep duration and phenotypic age in US adults: a population-based study

“…Findings from different cohort studies further corroborated our results, demonstrating a positive correlation between healthy sleep quality and improved cognitive health, as well as a decreased risk of premature health span decline [36][37][38] . Additionally, although not explored in this study, the impact of napping on sleep duration is a multifaceted aspect that requires careful consideration [39][40][41] . Further exploration is needed to understand the relationship between napping habits and overall sleep duration, particularly in the context of split sleep schedules and potential associations with sleep fragmentation.…”