Daytime napping after a night of sleep loss decreases sleepiness, improves performance, and causes beneficial changes in cortisol and interleukin-6 secretion

Abstract

Sleep loss has been associated with increased sleepiness, decreased performance, elevations in inflammatory cytokines, and insulin resistance. Daytime napping has been promoted as a countermeasure to sleep loss. To assess the effects of a 2-h midafternoon nap following a night of sleep loss on postnap sleepiness, performance, cortisol, and IL-6, 41 young healthy individuals (20 men, 21 women) participated in a 7-day sleep deprivation experiment (4 consecutive nights followed by a night of sleep loss and 2 recovery nights). One-half of the subjects were randomly assigned to take a midafternoon nap (1400-1600) the day following the night of total sleep loss. Serial 24-h blood sampling, multiple sleep latency test (MSLT), subjective levels of sleepiness, and psychomotor vigilance task (PVT) were completed on the fourth (predeprivation) and sixth days (postdeprivation). During the nap, subjects had a significant drop in cortisol and IL-6 levels (P < 0.05). After the nap they experienced significantly less sleepiness (MSLT and subjective, P < 0.05) and a smaller improvement on the PVT (P < 0.1). At that time, they had a significant transient increase in their cortisol levels (P < 0.05). In contrast, the levels of IL-6 tended to remain decreased for approximately 8 h (P = 0.1). We conclude that a 2-h midafternoon nap improves alertness, and to a lesser degree performance, and reverses the effects of one night of sleep loss on cortisol and IL-6. The redistribution of cortisol secretion and the prolonged suppression of IL-6 secretion are beneficial, as they improve alertness and performance.

Timing Matters: Circadian Rhythm in Sepsis, Obstructive Lung Disease, Obstructive Sleep Apnea, and Cancer

“…Animals undergoing septic challenge are less likely to recover when their 12/12 hour light/dark cycle is replaced by constant light or constant darkness (38,39). In humans, systemic C-reactive protein, IL-1, and IL-6 were increased in sleep-deprived individuals (40)(41)(42) …”

Minimal Effect of Daytime Napping Behavior on Nocturnal Sleep in Pregnant Women

“…10,11,19,23 Presently, pregnant women have received little attention with regard to daytime naps and their possible consequences BRIEF SUMMARY Current Knowledge/Study Rationale: Pregnant women report signifi cantly more nocturnal sleep disruption than non-pregnant women. We wanted to evaluate whether daytime naps either hindered nocturnal sleep or might be a "countermeasure" to offset poor nocturnal sleep.…”

“…[1][2][3] Emerging evidence indicates that insuffi cient quantity and poor sleep quality are associated with increased risk of mood dysregulation , 4,5 as well as adverse pregnancy outcomes, such as preterm birth and gestational diabete s. [6][7][8] When suffi cient nighttime sleep is not possible or unattainable, certain strategies can be implemented to counteract the negative effects of disturbed nocturnal sleep. One promising approach is to include daytime naps as part of a healthy sleep hygiene progra m. [9][10][11] There is limited information examining the effects of daytime naps on nocturnal sleep outcomes in non-pregnant populations. The majority of evidence stems from examination of daytime naps in elderly or middle-aged individuals or children.…”

“…The bulk, however, consider daytime naps as a positive health behavior (a "countermeasure") in that they can effectively combat subjectively reported poor sleep quality and decrease subjective daytime sleepiness by augmenting shortened nocturnal sleep durat ion. [11][12][13][14] However, there is also a small literature that suggests that naps can be detrimental to nocturnal sleep and next-day daytime alert ness. [15][16][17] Research on varied nap lengths shows that the greatest increase in aler tness, 10,1 8 mood, 19 or sleep…”

“…Given that poor sleep continuity and quality are important correlates of adverse pregnancy outcomes, 5 propose that a beneficial countermeasure to sleep disruption is daytime naps, which is in line with several other reports in non-pregnant cohorts. [9][10][11]41 Additional research is still needed to determine the effect of naps > 30 min on pregnant women.…”