Naps, Cognition, Performance – Review

This paper is one of the proceeds of a symposium held by the authors (“The Effect of Naps on Health and Cognition”, held at the 5th Congress of the World Federation of Sleep Research and Sleep Medicine Societies in Cairns, Australia, September 2007). It describes several research questions and nap-hypotheses, and an agenda for further research on naps is proposed.

Naps, cognition and performance. Gianluca Ficca, John Axelsson, Daniel J. Mollicone, Vincenzo Muto, Michael V. Vitiello. Sleep Medicine Reviews – August 2010 (Vol. 14, Issue 4, Pages 249-258, DOI: 10.1016/j.smrv.2009.09.005)

Practice points:

  • examination of the interrelationships of napping, cognition and performance in four specific contexts
  • the hypothesis that a split-sleep schedule provides more recovery than a single consolidated sleep period of the same total duration is examined. (Correctly timed split-sleep, shown to have positive effects, or at least no negative consequences on neurobehavioral performance, might be used for sleep-wake schedules in work environments that involve restricted nocturnal sleep due to critical task scheduling)
  • the advantages and disadvantages of napping in the work environment are examined. (Napping is an effective important countermeasure to maintain adequate performance levels during extended work shifts, and in operational settings. Napping strategies should be a natural part of programmes having the aim to improve safety and health in the work place. / Short day-time naps are effective on vigilance and cognitive functions for subjects with moderately disturbed sleep and possibly for normal sleepers. Actually, a nap as short as 10 min can improve alertness and performance for about 2.5 h if prior sleep loss exists and for almost 4 h if preceded by normal sleep)
  • benefits of napping for the learning of new material (Naps appear beneficial for memory consolidation of material newly acquired before the nap, either procedural or declarative. More robust effects seem to be given by slightly longer naps, about 60–90 min, possibly due to the build-up of both SWS and REM sleep)
  • whether regular napping among older adults, particularly those in good health, may be beneficial to daytime wakefulness or detrimental to night-time sleep propensity. (The prevalence of spontaneous napping increases with age in adults. This increase is likely the result of increases in nighttime sleep disturbances, phase advance of circadian rhythms, co-morbid medical and psychiatric illnesses and poor sleep habits. / Frequent, unplanned, longer daytime naps in older adults have the potential to negatively impact nighttime sleep quality and may be associated with significant negative health consequences such as increased risk of morbidity, cardiovascular illness, falls and cognitive impairment. / Brief planned naps may be of benefit to the function of healthy older adults, and perhaps even older adults in poorer health)

Research agenda:

  • How and to what extent the neurocognitive effects of naps may change as a function of their circadian placement should be explored in more details.
  • Further studies are needed if we aim to understand the combinatory effects of several countermeasures to maximize alertness at crucial time points: for instance, it would be important to verify how the use of naps and caffeine are best combined in operational shift-work settings.
  • It is still to be understood what sleep features are crucial for the “nap effect” on memory consolidation.
  • Lab studies could seek the effects of naps on specific higher cognitive functions using ad-hoc paradigms and tasks.
  • Research on naps and cognition should include the study of oneiric activity (i.e., dream features) during napping.
  • The cognitive effects of napping at early ages should be explored, because this might be of interest with respect to learning processes and school performance.
  • More elaborate self-report paralleled by objective assessment techniques, such as actigraphy, which allow for a better appreciation of the complexity of napping behavior, should be employed in large, representative samples of older adults which include both nappers and non-nappers.

Especially the second to last point is of interest to me. Would ‘younger children’ also include adolescents though?