By Peter M. Vishton, PhD, William & Mary

Edited by Kate Findley and proofread by Angela Shoemaker, The Great Courses Daily

Eight hours of sleep seems to be the magic number touted by parents, doctors, and popular media. In our fast-paced culture, this may not seem possible or practical. According to Professor Vishton, though, our happiness and even our survival is dependent on a good night’s sleep.

Is Eight Hours Necessary?

Is it really necessary to get eight hours of sleep? Many people report that they sleep less than eight hours on most nights; some even sleep less than five. Most of these people claim that they feel fine and, in fact, have a certain amount of pride in their ability to get along without “wasting” all of those hours doing nothing. 

Others may have a more fatalistic view—they may want to get more sleep, but that doesn’t seem possible—at least, not all the time. Either way, according to Professor Vishton, you can outsmart yourself by getting more sleep. 

First, though, you may be wondering why it’s necessary to get eight hours of sleep—especially if you’re one of those people who feels fine with seven hours of sleep or less. Will your life be substantially improved?

Consider this. There’s a common experience that many people have when they take a vacation.

Typically, the alarm clock gets turned off for many days in a row, and people sleep more than they normally would. At the end of this week of extra sleeping, many people report feeling fantastic: more energetic, excited about life, creative, motivated, and happy. 

Of course, just being on vacation contributes to these feelings, but this feeling often follows you when you return to work and regular life. It is the mental clarity that contributes to this positive experience.

If you’ve had this experience, there’s a lot of evidence that what you’re feeling is your brain functioning the way that it’s supposed to when it’s had a proper amount of sleep. According to Professor Vishton, the conventional wisdom is correct: You should get about eight hours of sleep a night, almost every night.

Getting More Sleep

A wide variety of data suggests two important things. First, when we don’t get about eight hours of sleep per night, our cognitive performance is substantially reduced. Second, we don’t realize our performance is less than optimal, which itself is dangerous, as it could lead to reckless driving or poor decision-making.

Professor Vishton recommends that you experiment with getting eight hours of good sleep every night for two weeks. Doing this will likely entail cutting out some other activities out from your daily schedule. 

You might have to work a little less. You might have to watch a little less television. The day will not get any longer for this experiment, so some shuffling of your schedule might be needed. However, it’s just for two weeks. 

“If, after the two weeks, you aren’t thrilled with the outcome, you can return this particular tip for a full refund,” Professor Vishton said.

What Is Sleep?

Let’s consider what sleep actually is—what your body and brain do while you’re asleep. Most people think of sleep as a time when your brain and the rest of your body shut down for a few hours. 

However, our brains remain very active when we sleep. There are certain jobs that the brain needs to do every night as part of its normal functioning. 

If the brain skips those tasks, the brain’s level of function will decline. Decision-making, memory, control of physical actions, emotional regulation, creativity, and even basic perception—all of these processes will become more prone to error.

This is true when people are prevented from sleeping at all for an extended period, but it’s also true for people who get somewhat less than eight hours of sleep for several nights in a row. Tests of intelligence, creativity, focus of attention, and memory all show lower performance with this cumulative sleep deprivation. 

In one study conducted in the European Union, it was estimated that 10 percent of all auto accidents involve people driving while drowsy. People who report that they sleep six to seven hours per night—which is very common—are twice as likely to be in a car crash as people who sleep for eight hours per night. Sleeping eight hours a night for two weeks just might save your life.

This article was edited by Kate Findley, Writer for The Great Courses Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.

Peter M. Vishton is Associate Professor of Psychology at William & Mary. He earned his PhD in Psychology and Cognitive Science from Cornell University. Before joining the faculty of William & Mary, he taught at Northwestern University and served as the program director for developmental and learning sciences at the National Science Foundation.