Seven Hours of Sleep May Be Better Than Eight

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You’ve probably heard that 8 hours is the magical amount of sleep needed every night. New research suggests that may not be the optimal amount for everyone.


Conventional wisdom states that eight hours of continuous nightly rest is necessary to refresh ourselves. Too little sleep and we’re tired in the morning. Moreover, a number of studies have shown that lack of sleep endangers our health and longevity. One recent study suggests that chronic sleep loss may lead to loss of brain cells.

At the other end of the scale, too much sleep increases our risk for health problems, including diabetes, obesity and cardiovascular disease.

Unfortunately, the ‘8 hours of sleep a night’ rule ignores common variations in individual sleep patterns, creates stress for people who aren’t able to get eight hours of sleep, and ignores a historical precedent.

Sleeping in one eight-hour block of time is a very recent phenomenon brought about by the industrial revolution at the end of the 19th Century. The dominant pattern of sleep, arguably since ancient times, was biphasic. People slept in two four-hour blocks, separated by a period of wakefulness in the middle of the night that lasted an hour or more.

Today, sleep experts generally recommend seven to nine hours of continuous sleep a night for healthy adults. However, a recent study provides the latest evidence that seven hours — not eight or nine — is the optimal amount of sleep for adults.

The study was published in the Journal of Clinical Sleep Medicine and evaluated five healthy adults that spent over two months in a “Stone Age-like” settlement in Southern Germany [1].

Participants lived in huts built on stilts with no electricity, clocks or running water. They  gathered their own food each day and returned to their beds made of brushwood and furs each night. There were no torches or candles in the huts.

The most notable finding of the study was that night time in bed and estimated sleep time increased dramatically. Study participants fell asleep about two hours earlier and got on average 1.5 hours more sleep than normal. Their average amount of sleep was 7.2 hours per night.

New sleep guidelines are coming

As American sleep less than they did in the past, sleep scientists are working to develop new guidelines that reflect evidence that has emerged from scientific studies. The National Healthy Sleep Awareness Project aims to figure out how to best update recommended sleep guidelines in 2015. The new sleep guidelines are expected to take into account variables such as gender and age. The guidelines will be determined by a panel of experts being assembled by the Centers for Disease Control and Prevention (CDC), the American Academy of Sleep Medicine, and the Sleep Research Society (an organization for sleep researchers).

The National Sleep Foundation, a nonprofit research and advocacy group, has also assembled an expert panel unrelated to the project above and expects to release updated recommendations for sleep times in January 2015.

All these groups currently recommend seven to nine hours of nightly sleep for healthy adults.

How much sleep do you need?

Because sleep needs vary between individuals due to both genetics and cultural differences, you should aim for seven to eight hours of sleep a night and evaluate how you feel. Experts say people should be able to figure out their optimal amount of sleep in a trial of three to seven days, ideally while on vacation.

Go to sleep when you get tired, avoid too much caffeine or alcohol, don’t use an alarm clock, and stay off electronic devices a couple of hours before going to bed. During your sleep trial, use a diary or a device that records your actual sleep duration to track your sleep. If you feel refreshed and awake during the day, you’ve probably discovered your optimal sleep time.

The amount of sleep you need every night changes over the course of your life. The National Heart, Lung and Blood Institute recommends seven to eight hours of sleep per night for adults, and more for teens. School-aged children should get at least 10 hours of sleep per night.

Source: The Wall Street Journal


  1. Piosczyk et al. Prolonged Sleep under Stone Age Conditions. J Clin Sleep Med. 2014 Jul 15;10(7):719-22. doi: 10.5664/jcsm.3854.
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About the Author

Jenny Jessen is a senior writer at Highlight HEALTH.