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The Complicated Science of Napping
When you’re exhausted, there’s nothing that compares to the feeling of an afternoon nap, and now a new study, published in the journal Sleep, explains why—and why this isn’t always a good thing.
After a sleep-deprived night, a nap the next day helps you catch up. As soon as you doze off the brain slips into slow-wave sleep, or SWS, which is the most important stage of sleep. SWS is marked by high-amplitude, low-frequency brain waves and is the deepest and most restorative stage of sleep. Your body is relaxed, your muscles are at ease, and your heart rate and respiration are at their slowest.
According to research, 74 percent of the population takes at least one afternoon nap per week, and those naps don’t affect the depth and quality of nighttime sleep.
So how could napping be bad?
In the new study, out of the University of Michigan, researchers examined the benefits of napping to offset the cognitive impairment of sleep deprivation.
The group who skipped a night’s sleep but had slipped into slow wave sleep during naps still experienced cognitive impairment as a result of sleep deprivation.
See also Why You Need 7 Hours of Sleep
The Ayurvedic Take on Napping
The Ayurvedic take on daytime sleeping, or divaswapna, is often misunderstood and will need some unpacking!
According to the Shushruta Samhita–one of the major Ayurvedic texts, you shouldn’t sleep during the day or keep late hours. In fact, it says that day sleep is forbidden in all seasons, except summer, and that all three doshas—vata, pitta, and kapha—are aggravated by day sleep. Then, confusingly, the Shushruta Samhita gives a fairly extensive list of reasons why and when it is actually ok to take an afternoon nap. Let’s dig in!
From the Ayurvedic perspective, afternoon naps for 48 minutes, or one muhurta, are permitted for children, the elderly, and those who are emaciated, exhausted from travel, over exerted, have done hard physical labor, people who have not eaten food, or those who have been up all night (Shushruta Samhita, Ch IV. Verse. 35-37).
The Shushruta Samhita says that daytime sleeping will aggravate all the doshas due to a “perversion of nature,” Which modern science has described nature as a circadian imbalance, in which your biological clocks and therefore metabolism, are out of sync with nature’s light and dark rhythms.
Sleeping during the day because you didn’t sleep well the night before will aggravate kapha and, as the University of Michigan study suggests, increase kapha imbalances that can lead to fatigue and obesity.
The Shushruta Samhita allows for short afternoon naps in the summer because summer is the one season that most affectively balances kapha and vata. The summer’s heat helps to dry up excess kapha and also warms vata, the first dosha to become imbalanced with sleep deprivation or overexertion.
Other Risks Associated with Napping
In a study published in the American Journal of Epidemiology more than16,000 men and women were evaluated for their napping habits. At the 13 year follow-up, controlling for a litany of other risk factors, there was a significantly increased risk of all-cause mortality for those who took a daily, short (less than an hour)afternoon nap.
In another study, published in the Journal of the American Medical Association Network Open, more than 136,000 participants from 24 countries were evaluated for cardiovascular risk factors associated with later bedtimes and afternoon naps. One of the primary risk factors of heart disease is belly fat. In this study, those who got less than six hours of sleep per night experienced greater rates of general obesity, while those who took regular afternoon naps to help offset their sleep deficits had higher rates of belly fat, which is a more concerning risk factor.
The answer to whether regular napping is beneficial seems to align with the Ayurvedic texts. There are circumstances when naps are okay and there are times when they can be harmful in the long-term. It all depends on why you’re taking a nap in the first place.
On the bright side, for those who love naps there is no shortage of studies linking a short afternoon nap to better performance, mood and, more energy.
To Nap or Not to Nap?
According to the science, it seems that naps can be good or bad depending on why you are taking them and for how long the nap lasts. If you’re sleep deprived, a nap may be necessary, but a nap is not an adequate replacement for a good night’s sleep. If you’re in need of a nap every day for more than an hour, this could be a sign of a health concern that should be evaluated medically. Taking a nap as a result of a late night or over exertion may offer health benefits.
If you are an afternoon napper and its making you feel better, then continue this practice. But stop to evaluate whether your naps are a response to overexertion, exhaustion, or some other energy deficit that keeps you out of sync with the seasons and circadian rhythms.
Don’t confuse an afternoon nap with an afternoon post big meal rest that is best done by lying on your left side after a meal for 10-15 minutes. This isresting, not sleeping.
See also The Wisdom of Siestas