News & Views

To nap or not to nap – that is the question

By Zach Pearl, PhD
Circadin.com Staff

Inadequate sleep can have a major impact on a person’s health, safety, mood and work performance. Unfortunately, research indicates that over the last decade more people worldwide have been getting less sleep than needed. This can initiate a spiral towards fatigue and sleepiness. Napping can be one way of recovering a bit of the sleep debt that many people live with every day.

What is a nap?

A nap (Siesta) is a short period of sleep typically taken in the afternoon. The name siesta is derived from the Latin: hora sexta, “the sixth hour” (counting from dawn, therefore noon). The afternoon siesta is an integral part of many different cultures throughout the world, particularly those with warm weather.

Why do we need to nap?

Most mammals sleep for short periods of time throughout the day, while humans have combined sleep into one long period. The biological clock pattern is wakefulness during the day followed by gradually increasing sleepiness in the evening. However, it is also common to have a little dip of mid-afternoon sleepiness which causes people to feel drowsiness and a desire to nap1. The frequency of spontaneous napping increases in adults with age. This is likely to be a result of an increase in nighttime sleep disturbances, phase advance of circadian rhythms (a shift in sleep hours), co-morbid medical and psychiatric illnesses and poor sleep habits.

Benefits of napping

Increases alertness – Studies have shown that if you divide your day with a nap, you will be as alert and energetic in the second part of your day as you were in the first2. A NASA study found that a 40-minute nap increases alertness by 100%3. It was also found that even a 10-minute nap can improve alertness and performance for about 2.5 hours in case of deprived sleep and for almost 4 hours in case of having a normal nighttime sleep4 5.

Improves learning and consolidation of memories – Naps improve the working memory, which is a type of memory involved in working on complex tasks6. Naps were shown to have a positive influence on cognitive tasks following a night of deprived sleep2.

Improves physical performance and productivity – Studies show that following a 30-minute nap, physical performance and alertness were increased, and sleepiness was decreased. Naps can significantly reduce sleepiness and be beneficial for learning skills, strategy or tactics. Napping could also benefit athletes who wake up early to train, compete or travel and for those experiencing sleep deprivation2 7. Another study found that a short afternoon nap of 20 minutes yields mostly stage 2 sleep, which enhances alertness and concentration, elevates mood, and sharpens motor skills8.

Improves health – Napping could reduce blood pressure and fend off heart attacks. In 2007, a study found that nappers were 40% less likely to die from heart disease than non-nappers9. Daytime napping for 45 minutes has also been shown to lower blood pressure and improve the rate of cardiovascular recovery after mental stress10.

Improves mood – Napping has been shown to boost the immune system and have stress-releasing effects11. A short nap of about 20-30 minutes, has been shown to provide significant benefit for improving mood12.

People who suffer from narcolepsy or shift-work syndrome13 may also benefit from daytime naps.

Disadvantages of napping

Napping may be a unhealthy habit and it does not fit everyone.

Sleep inertia – A long nap may lead to an overly tired feeling, disorientation and grogginess. This is because in longer naps the brain enters the slow-wave sleep phase (deep sleep). It generally disperses within 30 minutes but can cause difficulties if one is required to perform at a high state of awareness directly after the nap14.

Increased risk of diabetes – There are some recent studies that show that daytime napping was associated with an increased risk of type 2 diabetes, particularly when it is combined with a short nighttime sleep duration15 16.

A risk factor for morbidity and mortality – Contrary to the popular view that naps are beneficial for health, long or frequent naps can be risky. They might be associated with worse long-term health and increased mortality in the elderly population17 18 particularly in those persons requiring naps because of an unrecognized disease or nighttime sleep deprivation.

Nighttime sleep problems – Short naps usually do not affect nighttime sleep quality. However, if one suffers from insomnia or poor sleep quality at night, napping might worsen these problems. Napping may shorten nighttime sleep, decrease sleep efficiency and lead to an earlier morning rise4.

Daytime sleepiness can also be a sign of a health problem such as Parkinson’s disease19 or depression. In studies of older people, regular napping has been associated with diabetes, depression and chronic pain, presumably because those conditions adversely affect nighttime sleep.

Tips for a good nap

  • Keep it short – 10-30 Minutes nap produces the most benefit in terms of reduced sleepiness and improved cognitive performance20. A nap longer than 30 minutes is more likely to be accompanied by sleep inertia. Remember, napping later in the day can interfere with falling asleep at night, and disrupts the body clock
  • Get comfortable — Choose a cool, dark and quiet room to help you fall asleep and have a restful nap
  • Choose the right time to nap — Taking naps at a regular time of day will help maintain your body’s natural sleep cycle. The ideal nap zone is between 13:30-15:30. Your body may not be ready for more sleep if it is early in the day, while napping too late can cause problems falling asleep at bedtime

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