8 Hours? 9 Hours? This Is How Much Sleep You REALLY Need

Ask anyone how much sleep they should be getting and most people will tell you 8 to 9 hours. But new research suggests that you might actually need less sleep than that — possibly as little as 7 hours for full rest and maximum health benefits.

A recent Wall Street Journal article examined several sleep studies and concluded that most people would be better off with 7 hours of sleep than with 8 or 9 hours. Getting too much sleep may be just as harmful or even more harmful to your health than getting too little sleep. So, why is 7 hours better? (See also: 7 Ways to Sleep Better in Fewer Hours)

One study examined by the article tracked the self-reporting habits of 1.1 million people and found that those reporting 6.5 to 7.4 hours of sleep had lower mortality rates than those getting more or less sleep. Another study used a device to track how much sleep 450 elderly women got and concluded that those women getting more than 6.5 hours or fewer than 5 hours of sleep had higher mortality rates.

Perhaps my favorite study involved placing five adults in "Stone Age like conditions" in Germany for over two months. They didn't have electricity, clocks, or running water. The study found that "participants fell asleep about two hours earlier and got on average 1.5 hours more sleep than was estimated in their normal lives." Their average amount of sleep per night: 7.2 hours.

As a sleep deprived mother of a 4-week-old I have a hard time believing that getting too much sleep can be just as harmful as getting too little sleep. (Especially after reading this study that shows that new moms are dangerously exhausted for months after their little ones are born.) But being so sleep deprived, 7 hours of sleep currently does sound like a lot.

So, if, on average, people only need 7 or 7.5 hours of sleep, how do you know how much sleep you need?

Factors to Determine How Much Sleep You Need

The following factors influence how much sleep you need.

1. Your Gender

Women need more sleep than men, by an average of about 20 minutes a night. And pregnant women in their first trimester need even more sleep than that.

2. The Quality of Sleep You're Getting

Anyone who is frequently awakened by the blaring siren from the fire station down the street or the cries of a hungry newborn knows that 7 hours of uninterrupted sleep is extremely different from 7 hours of pieced together, interrupted sleep. Similarly, sleeping on rocky ground while camping or on your in-laws pull-out couch is much different that your own mattress. The better the quality of your sleep, the less you'll need.

3. How Much "Sleep Debt" You're In

If you've been skimping on sleep for awhile you likely will need more sleep to catch up than if you are continually well-rested.

4. Your Age

Newborns sleep up to 20 hours a day, toddlers 11-14 hours, twenty-somethings 7.5 hours, and the downward trend continues up to 80 year olds who sleep less than 6 hrs a day. So, depending on your age, you may need more or less sleep than others.

5. Your Genes

As with most differences between individuals, genes play a role in how much sleep you need. If you're someone who has almost always needed a lot of or very little sleep, chances are your genes are playing a role, too.

How much sleep do you get a night? Do you feel like it's too little, enough, or too much?

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Guest's picture

When your body can wake up without the aid of an alarm, that is how much sleep you need. If you have a hard time getting out of bed, you should probably go back in it. I actually think 8 1/2 hours is the sweet spot but that's just my 2 cents. Everybody is different. Listen to your body, eat well and exercise.

Guest's picture

How about the fact that people who are ill are both more likely to have a higher mortality rate and to sleep longer. It seems they mixed up cause and effect.