Sleep myths and facts

Visit our forums to chat with other Canadian Living readers.

I can get by fine on four or five hours of sleep
It's true that a small percentage of people are short sleepers who only need five or six hours of sleep per night. However, sometimes it seems as if two-thirds of the population believe they belong to this select group.

The overwhelming majority of people need seven to nine hours a night, so the chances are relatively small that any particular individual is truly a short sleeper. To calculate your sleep need, follow the instructions in Chapter 3.

If you need eight hours a night but only get six, you can usually carry on for a day or two. After a few days, you'll start to show signs of sleep deprivation, such as daytime drowsiness, irritability, and decreased productivity, and you'll also place yourself at a higher risk for safety problems at work and behind the wheel.

You can learn to get by on less sleep
Unfortunately, there's no way to train the body to reduce its sleep need. Studies on chronic partial sleep deprivation, restricting people to only four or five hours of sleep for several weeks, found that people continue to get sleepier and their performance becomes more impaired the longer the study goes on. There is no plateau or limit to how sleepy and impaired they get. To meet a job deadline or study for a final exam you may be able to function on less sleep, but you will feel more tired, work less efficiently, and get less done.

Insomniacs barely sleep at all
People with insomnia often announce in the morning that they "didn't sleep at all last night." Although it may have seemed this way, failing to get any sleep is extremely unlikely. Even in severe cases, people with insomnia typically get a few hours of sleep per night. We all tend to be poor judges of how long it takes us to fall asleep and how long we've slept. Everyone has had the experience of intending to fall asleep for a few minutes and waking up several hours later, unaware of how much time has passed. This is because we don't experience the passing of time while asleep. There is a small group of people who are convinced they get no sleep at all each night -- until we bring them into the sleep laboratory and show them that although they claimed to lie awake all night, they actually slept for seven hours.

Falling asleep during the day is a sign of laziness
Falling asleep during daytime hours is not a character defect; it's a sign of physiological need. Lazy people may fritter away their time at unproductive or pointless tasks, but they don't necessarily have trouble staying awake in the daytime.

Sleeping during the day is a sign of sleep deprivation. This can be self-induced (that is, from staying up late), or it may result from poor sleep hygiene; insomnia; sleep apnea, narcolepsy, or another sleep disorder; or an underlying illness. It can also be a side effect of a medication.

Listening to self-help recordings while you sleep can help you learn
Although a multitude of tapes and CDs are available on the Internet purporting to help people improve themselves (such as learn a language, lose weight, or quit smoking) while they sleep, I've yet to see any solid research showing they're effective. What sometimes confuses this issue is that there is abundant evidence that a good night's rest can improve test performance compared to a night of sleep deprivation. Sleep does play a role in learning, but first you need to be awake while you're taking in new information.

Page 2 of 3

Excerpted from The Harvard Medical School Guide to a Good Night's Sleep by Lawrence J. Epstein, M.D., with Steven Mardon. Excerpted by permission of McGraw-Hill. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.