How Much Sleep Do You Need, Really?

By Haley Bass | 10/26/2016

We spend up to a third of our lives asleep, so it’s important that we make the most of that time.

Good sleep is necessary for good health because it’s such a vital, time-consuming part of our lives. However, we tend to push sleep down on our list of priorities, relying instead on caffeine and sugary snacks to get us through the day. 

Sleeping in during the weekend and downing energy drinks isn’t going to pay off your sleep debt, and not getting enough sleep can lead to some serious health risks.

“Generally speaking, the proper amount of sleep is the amount that allows the individual to wake refreshed and to remain alert throughout the day without the need for caffeine or other stimulants,” says Dr. Nathaniel Watson, MD and president-elect of the American Academy of Sleep Medicine (AASM).

How Much Sleep Do You Need?

Based on evidence from several studies, experts from the AASM and the Sleep Research Society have determined that around seven hours per night seems to be the optimal amount of sleep for the average adult. Sleeping under five hours or over eight hours every night could potentially be dangerous for your health.

  • A frequently-cited 20-year study completed by UC San Diego and the American Cancer Society, found that individuals who slept for close to seven hours per night lived longer than those who slept eight or more hours. And poor health can contribute to the cause of excessive sleep.
  • A study completed with data from Luminosity, a site dedicated to improving cognition, found that cognitive performance peaked at about seven hours of sleep, but began to slowly drop off beyond seven hours.
  • A 2014 study focused on the cognitive abilities in women aged 70 or older, determined that sleeping nine hours or more was just as harmful as sleeping five or fewer.
  • A newer study by experts in Norway and Taiwan, found that the risk of heart disease increased 50% for individuals who slept less than four hours per night, compared to those who slept between four and eight hours. Evidence also showed that those who slept more than eight hours a night had a 53% greater risk of dying from coronary heart disease.

Despite the recommendation, Dr. Watson still offers this warning: “It’s important we note that no study will tell an individual exactly how much sleep they personally need — we can’t take these studies and make individual recommendations.”

Sleep Debt

Even if you can still function on little sleep, you won’t be functioning at your peak ability. David Dinges, a sleep scientist at the University of Pennsylvania, said that regularly getting even just 20 to 30 minutes less sleep than the recommended seven hours can slow cognitive speed and increase attention lapses. 

When you skimp on sleep, a chemical in the brain that makes you sleepy (adenosine) doesn’t have time to break down in the body, so you get more desperate for sleep throughout the day and your reaction time slows. Insufficient sleep has caused about 100,000 traffic accidents, 76,000 injuries, and 1,500 deaths a year. Between health care expenses and lost productivity, America’s sleep debt puts us in the hole about $66 billion annually.

Find Your Optimal Sleep Time

Make sleep a priority, and try to figure out the optimal amount of sleep for you. Find a period of time where you have a flexible schedule. During that span, go to bed at the same time every night, don’t set an alarm clock, and record how many hours you slept in the morning. If you feel refreshed and awake during the day, you’ve found your optimal sleep time.

Having trouble falling asleep? Check out our Tips and Tricks to Get Back to Sleep.