Background

Sleep deprivation impairs a wide range of cognitive processes, including vigilant attention and placekeeping, which are particularly important. Vigilant attention is the ability to maintain consistent attention over time, and placekeeping is the ability to complete a series of steps in a prescribed order without repetitions or omissions in the face of distractions and interruptions. Given the consequential effects of sleep deprivation, there is great interest in finding new ways to mitigate them. Napping has shown promise as an intervention, but most studies have used naps spanning several hours.[1][2] Do brief naps have the same effects?

The study

In this randomized controlled trial, 280 participants (aged 18–26) completed a placekeeping task (UNRAVEL) and a vigilant attention task (Psychomotor Vigilance Task [PVT]) in the evening and were subsequently assigned to stay awake overnight in the laboratory or go home and sleep. In the sleep-deprived group, the participants received either a 0-minute, 30-minute, or 60-minute nap opportunity between 4 and 6 a.m., followed by all participants completing the UNRAVEL and PVT at 8:30 a.m. Polysomnography was used to monitor sleep during the nap opportunity, and wrist actigraphy was used to monitor participants who were sent home to sleep.

The results

Sleep deprivation significantly impaired performance on both tasks, and the nap opportunity had no meaningful effect on the magnitude of impairment.

The regression analysis found that more slow-wave sleep during the nap opportunity was associated with improved performance on both tasks. Also, longer sleep onset latency during the nap was associated with improved reaction time on the PVT. In the sleep group, total sleep time was associated with improved reaction time on the PVT.

Note

Despite the inclusion of multiple outcomes, the authors did not adjust for multiple comparisons, which increases the risk of false positive findings. Therefore, the results should be considered exploratory.

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This Study Summary was published on September 1, 2021.

References

  1. ^M Mila Macchi, Ziad Boulos, Thomas Ranney, Lucinda Simmons, Scott S CampbellEffects of an afternoon nap on nighttime alertness and performance in long-haul driversAccid Anal Prev.(2002 Nov)
  2. ^A N Vgontzas, S Pejovic, E Zoumakis, H M Lin, E O Bixler, M Basta, J Fang, A Sarrigiannidis, G P ChrousosDaytime napping after a night of sleep loss decreases sleepiness, improves performance, and causes beneficial changes in cortisol and interleukin-6 secretionAm J Physiol Endocrinol Metab.(2007 Jan)