Neurobiological Effects of Synchronized Sleeping
The need to nap for long stretches may be a reflection of an underlying health problem.
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BRIEF COMMUNICATION
Sleep, while necessary for survival, can be compromised due to factors such as busy schedules or insomnia. Alternate sleep schedules, such as napping and splitting sleep duration, can change sleep quality and have an effect on waking concentration and performance.
Napping
Naps are common in many cultures. They are not practical for people who have a long workday, but they may have value in providing restorative sleep in certain circumstances.
Epidemiological studies suggest that short naps with duration between 10 to 30 minutes can enhance productivity. Long naps, however, have been associated with increased morbidly and mortality.1 Some research suggests that naps themselves are not harmful, but the need to take extended naps may be an underlying health problem.2
Splitting Sleep
Sleep duration has been studied extensively, and it appears that the average person needs between 7 to 9 hours of sleep on a regular basis. It has been unclear whether it makes a difference if that sleep should be attained all at once or whether it can be divided into a few short episodes. Dividing up sleep, unlike napping, involves sleeping for several hours at a time within a 24-hour period instead of an extended period of time with a very short burst of sleep.
A study by Kosmadopoulos and colleagues3 showed that volunteers who had their sleep schedules divided into two equal halves throughout a 24-hour period achieved the same amount of actual sleep as volunteers who slept in one long stretch as measured by polysomnography.
Another study by the same researchers a few years later gave two separate groups of volunteers the same total amount of 10 hours in bed per day.4 One group was given a long stretch of sleep, and the other group was given the same total amount of time in bed, but it was divided into two sessions. The group with the divided sleep tested lower on neurobehavioral measures of alertness than those who had the long stretch of time in bed.
The results of the two studies suggest the following:
• Divided sleep may not achieve the same restorative effects as a long stretch of sleep, despite the polysomnographical evidence of actual attained sleep
• Dividing sleep into approximately equal portions throughout the day does not have the same effects as napping
Recovery
Recovery after days or weeks of a disrupted sleep schedule does not necessarily occur after one good night’s sleep. Researchers aren’t sure how many days of good sleep it takes to recover.5
Overall, manipulation of sleep schedules and compromising on sleep is possible, but the short- and long-term results are not optimal for immediate performance or for overall health. Napping for short periods of time is not problematic-but the need to nap for long stretches may be a reflection of an underlying health problem.
References:
1. Dhand R, Sohal H. Good sleep, bad sleep! The role of daytime naps in healthy adults. Curr Opin Pulm Med. 2006;12:379-382.
2. Owusu JT, Wennberg AMV, Holingue CB, et al. Napping characteristics and cognitive performance in older adults. Int J Geriatr Psychiatry. 2018;Oct [Epub ahead of print].
3. Kosmadopoulos A, Sargent C, Darwent D, et al. The effects of a split sleep-wake schedule on neurobehavioural performance and predictions of performance under conditions of forced desynchrony. Chronobiol Int. 2014;31:1209-1217.
4. Short MA, Centofanti S, Hilditch C, et al. The effect of split sleep schedules (6h-on/6h-off) on neurobehavioural performance, sleep and sleepiness. Appl Ergon. 2016;54:72-82.
5. Banks S, Van Dongen HP, Maislin G, Dinges DF. Neurobehavioral dynamics following chronic sleep restriction: dose-response effects of one night for recovery. Sleep. 2010;33:1013-1026.
