Skip to main content

Verified by Psychology Today


Latest Study Says 7 Hours Magic Number for Healthy Sleep

Finding the perfect amount of sleep for maximum health.

Key points

  • New research says seven hours of daily sleep is optimal for a healthy life.
  • Findings supersede earlier beliefs that eight or nine hours of sleep are required to achieve maximum health.
  • Tips for quality sleep include: turning off your mind, not looking at the clock or screens, and no caffeine.
Pexels photo by Andrea Piacquadio
Source: Pexels photo by Andrea Piacquadio

When it comes to sleep, seven may be the new magic number.

Authors of a large population study, published in an April 2022 issue of Nature, indicated seven hours of daily sleep is optimal for a healthy life.

The scientists analyzed information from nearly 500,000 individuals between the ages of 38 and 73 and measured factors like cognitive performance, including visual processing, problem-solving, decision-making skills; mental health; and overall well-being.

The findings supersede earlier beliefs that eight hours of sleep or, according to the National Sleep Foundation, up to nine hours for those between 26 and 64 years old are required to achieve maximum health.

This is good news, especially for those concerned about cramming eight hours of sleep time into busy daily schedules or those so obsessively worried about getting enough sleep that their anxieties make falling or remaining asleep difficult or cause them to experience reduced quality of sleep architecture (necessary stages of sleep).

The results of this latest study, one in a series of sleep-duration studies during the past 15 or more years, are not surprising.

In 2018, University of Western Ontario scientists, writing in the journal SLEEP, suggested seven hours to eight hours of sleep as best for peak brain function and performance.

That study involved a global sample of more than 10,000 individuals who completed an online questionnaire. Authors wrote that “cognitive performance, measured [by] using a set of 12 well-established tests, is impaired in people who report typically sleeping less, or more, than seven-to-eight hours per night.”

The investigators also found self-reported sleep duration of four or fewer hours associated with the equivalent of “eight years of aging” in terms of overall cognitive abilities. They said, “sleep-related impairments in cognition affect all ages equally.”

Eight years earlier, investigators, also reporting in SLEEP, found

No evidence that sleeping habitually between six and eight hours per day [for] an adult is associated with [any] harm and long-term health consequences. In terms of prevention, consistently sleeping six to eight hours per night may therefore be optimal for health.

The Long and Short of It

Although the seeming focus of most people is on the health consequences of insufficient amounts of sleep, too much sleep can be equally detrimental. In a just-published article (June 2022), scientists suggested an “upregulation (heightened activity) of neuroinflammatory processes and ineffective beta-amyloid clearance [in the brain]” when sleep is deficient and “common report[s] of mental fatigue” in the sleep of longer duration.

Mental fatigue, of course, inhibits cognitive performance. Of even potentially greater significance is a study in a January 2022 issue of Frontiers in Medicine, in which investigators reviewed 36 sleep studies and conclude that evidence “highly suggests” an association between long sleep duration and an increased risk of mortality from all causes.

Other research, published in 2018 in Sleep Medicine Reviews, contended that “long sleep duration is associated with a significant increase in risk for mortality and incident diabetes, cardiovascular disease, stroke, coronary heart disease, and obesity.”

Stop the Worry

But whatever the recommended sleep duration–six, seven, or eight hours, people should stop wringing their hands over the precise amount of sleep they may be getting–or not getting–every night. Individuals too focused on sleep may actually be worsening the overall quality of their sleep and encouraging the development of sleep disorders, such as insomnia.

In fact, most recent statistics indicate that 10 percent to 30 percent of all adults struggle with chronic insomnia, which is a habitual inability to fall asleep, remain asleep, or awaken too early. That insomnia percentage is reportedly as high as 48 percent in older adults. About 40 percent of insomnia cases are linked with other mental disruptions like anxiety, depression, and post-traumatic stress disorder (PTSD).

Sleep can be akin to a finger trap–the harder one pulls, the worse the problem gets. Taking a line from Fight Club, a movie based on a book by Chuck Palahniuk, When you have insomnia, you’re never really asleep, and you’re never really awake.

If worried about hours of sleep, one should keep in mind a 2018 science article in the journal Nature and Science of Sleep. In it, sleep experts contended there may be,

no magic number in terms of the ideal sleep amount to obtain each night. Sleep duration recommendations are meant for public health guidance but need to be individualized to each [person]…Sleep needs are determined by a complex set of factors, including…genetic makeup [and] environmental and behavioral factors.

Recipe for Quality Sleep

So, what are the ingredients for quality sleep? Here are some common–and, perhaps, not-so-common–suggestions:

  • Turn off your mind. To quote computer scientist and mathematician Donald Knuth, “The hardest thing is to go to sleep at night when there are so many urgent things needing to be done.” But guess what? Not a whole lot one can do about those “urgent things” from bed. Shut down mentally, close your eyes, and know plenty of time will be available to consider matters in the morning.
  • Use the daytime hours to list “urgent things” and then cross them off the list as they are completed. When the mind tries to reprise matters at bedtime, one can mentally check off each as “done” and go to sleep.
  • Stop looking at the bedroom clock. Clocks do not provide any sleep incentives. They only make one increasingly anxious about getting needed sleep hours. Throw a cloth over the clock or place it, face away, in a hard-to-reach location.
  • Can’t fall asleep? After about 20 minutes, arise and do something relaxing like listening to soft music or reading a book until sleepiness returns.
  • Maintain regular bed and wake times, keep the bedroom cool, and move the TV to another room. Bedtime is for sleeping, not for watching television.
  • Adequately prepare for sleep by diminishing activity–particularly online and phone activity–an hour or two before bedtime. In a 2014 poll, one of four individuals between 18 and 24 blamed an inability to sleep well on technology. Remember the axiom, “Tech off at ten.”
  • Avoid caffeine, alcohol, and strenuous exercise just before bedtime.

Finally, if a person is already experiencing insomnia, he or she should consider maintaining the same wake time but going to bed later each night. This practice “squeezes sleep” by restricting time in bed and helps re-associate bed with sleep. The intent is to achieve sleep efficiency of 85 percent, calculated by time of sleep versus overall time in bed.

In the words of the ancient Greek author Homer, There is a time for many words, and there is also a time for sleep. So, go to sleep.

More from Alex Dimitriu M.D.
More from Psychology Today