A nap is more than just a health habit. In some cultures, it’s been incorporated into the daily routine, with work and other responsibilities literally built around the daily nap. Still, important questions remain unanswered regarding the benefits of naps. Is there a real measurable benefit to napping?
The National Sleep Foundation has collected all the existing literature to try to provide answers on the benefits (real and perceived) of a naps. A recent poll indicated that 46 percent of people in the U.S. nap at least once per week and the average duration of the nap is one hour. The following are a series of questions and answers on naps and sleep:
What type of napper are you?
Preparatory naps are occasional planned naps when you know you may be staying up late that night.
Emergency naps are when you find yourself suddenly very tired and you simply can’t continue with an activity you are engaged in.
Habitual naps involve the practice of taking a nap at the same time daily for a regular duration of time.
Part of the Sleep Foundation survey and poll compared individuals who were habitual nappers to individuals who just took naps when they had excessive daytime somnolence due to factors that affected the prior night’s sleep. There was a clear difference in cognitive improvement and performance in vigilance tests in those who were the habitual nappers.
A British 2008 study found that compared to getting more nighttime sleep, taking a daytime nap helped individuals to overcome the “afternoon slump” even better than a dose of caffeine.
Does the “timing of the nap” make a difference when it comes to providing benefits?
The body’s circadian rhythm directs the physiological functions of hormonal secretion, body temperature, and the states of wakefulness and sleep. It would make more sense to take a nap during the time in the cycle when there is a drop in the state of wakefulness. This would be at night after the brain has been used for many hours and has accumulated signals suggesting that it now needs to rest. There is also a period in the early afternoon when there is a drop in the body’s metabolic rate, and that would be the ideal time to take a nap.
Everyone who naps doesn’t necessarily follow their internal schedule in order to perfectly time a nap. In fact, most people just don’t keep to a regular schedule. This is especially true in the case with working people on night or rotating shifts, and it’s also true of the elderly who live alone. They are not bound to time constraints and will often have an irregular sleep-wake schedule.
Not surprisingly, the survey found that it was the regular scheduled nap (habitual) at the proper time that had the greater restorative benefits, helping to strengthen the waking periods and ameliorating the periods of metabolic slowing.
Taking a nap in the later period of the day, closer to bed time, will likely interfere with the ability to initiate sleep. So even though it may be tempting to shut your eyes after dinner, don’t. It will likely interfere with your nightly sleep.
What is the ideal duration of a nap? Is a longer nap better?
A short healthy nap should last for 20-30 minutes or less. A longer nap allows you to enter a deeper stage of sleep (delta). If you suddenly wake up from that deeper phase, you will likely experience “sleep inertia.” Sleep inertia (grogginess and incomplete awakening) can cause a reduction in the ability to think clearly and it can also limit one’s ability to perform complex tasks upon awakening. As REM phase of sleep doesn’t occur until 90 minutes after sleep is initiated, a shorter nap will prevent this deeper sleep phase and the risk of sleep inertia.
One other important factor is the amount of wakefulness the person feels prior to the nap (or the extent of sleep deprivation) which affects the risk of experiencing sleep inertia. If your nap is not compensating for poor nightly sleep habits, then you are less likely to enter deep sleep during the nap and experience sleep inertia. That’s also why a “power nap” that lasts about 10 minutes is not usually associated with sleep inertia. A regular nap habit decreases the chance of sleep inertia because it is not compensating for sleep loss at night; it’s intercepting and mitigating the natural daily metabolic slump.
Can older adults benefit from regular naps?
Napping has been proven to benefit young adults under the proper circumstances. Older adults are generally sleepier because their sleep quality is not as good. They also have more opportunity to nap because of availability of time and the amount of time spent in the home sitting and reading or watching TV. The National Sleep Foundation survey showed that the frequency of taking naps increases with every five-year increase in age.
The survey also found that:
Given that sleep is less restorative with advancing age (seniors spend less time in deep delta sleep) the theory is that older adults may need a longer nap to accrue the same benefits that younger adults get with a power nap or slightly longer nap.
The restorative effect of a nap was increased in older individuals who also engaged with regular daily exercise. The association of good quality sleep with exercise has been a subject of investigation, but this is the first time that it was shown in older adults.
What factors determine whether or not there is a positive payoff from a nap?
- The quality and regularity of sleep at night
- The regularity of the wake-sleep schedule
- The timing of the nap
- The duration of the nap
- The age of the individual
- Identifying/treating other conditions that cause daytime sleepiness
- Having a regular and daily exercise habit
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Can You Be Asleep When You're Awake?
Short Sleep and Poor Sleep Are Heartbreakers
Eli Hendel, M.D. is a board-certified Internist and pulmonary specialist with board certification in Sleep Medicine. He is an Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, Qualified Medical Examiner for the State of California Department of Industrial Relations, and Director of Intensive Care Services at Glendale Memorial Hospital. His areas of expertise in private practice include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases.