Get More Sleep! Avoiding The Perils Of Sleep Debt

An Outreach Project by Nick Wenner | Return To Outreach Projects 2010

My name is Nick Wenner, and I grew up in Klamath Falls and graduated from Klamath Union High School in 2007. With homework, socializing, jazz band at 7 AM every morning, and cross-country practice, I usually got about six hours of sleep each night during the week when I went to KUHS. As a result, I was usually tired during the day, especially in the afternoons.

This only got worse in my first two years of college at Stanford University. I am now in my third year at Stanford and I am taking a class entitled "Sleep and Dreams." In this class, I have been learning the science of sleep from William C. Dement, one of the primary researchers and founders of the discipline. I have been surprised by how little I knew about the 1/3 of my life I have spent in bed. I have written this Letter the Editor to share the most important thing I've learned in class: The concept of sleep debt.

What is sleep debt?

"Sleep debt" refers to the observation that sleep deprivation is an additive process: Every hour of sleep a person gets less than his or her nightly requirement appears to be carefully registered by the brain as a debt, and this debt appears to be added nearly hour for hour over time and must be "paid off" at a later date in order to regain full function of those factors affected by sleep loss. This means a night of sleep lost several weeks ago may very well continue affecting your mood, awareness, and general health until that sleep is paid off!

What are the effects of sleep debt?

Carrying a large sleep debt can seriously affect mood, physical health, and general wellbeing. One of the most obvious effects of carrying a large sleep debt is the tendency to feel drowsy throughout the day and a strong tendency to fall asleep during sedentary activities such as working at a computer or--often to fatal consequences--driving.

How do we know sleep debt exists?

Researchers learned that human beings could unknowingly carry a large sleep debt in a study that aimed to study the effect of light sources on sleep. In part of the experiment, carried out by Dr. Thomas Wehr and his colleagues at the National Institutes of Health, subjects were left in bed in the dark for 14 hours every night for 35 days.

At the beginning of the study, total daily sleep times for subjects jumped to amounts above 12 hours on the first night and then gradually declined. By the fourth week, the sleep time for the group had leveled off at a nightly average of a little over 8 hours. The interpretation is that the subjects went into the study unknowingly carrying a substantial sleep debt. Once the subjects were able to pay off this sleep debt in the first weeks of the study, they reached a steady state where they slept the same amount each night and could not sleep longer than that amount. The subjects reached a steady state value of about 8 hours of sleep per night, which means they lay in bed in the dark with nothing to do for about 5 hours each night!

This leads to an important insight: Contrary to popular belief, you cannot physically sleep too much! Once you have paid off your sleep debt, you will not be able to sleep for more time than you physically need and you will no longer feel sleepy during the day.

How much sleep debt do I have?

A simple way to gauge the amount of sleep debt you are carrying around is to notice how fast you fall asleep at night after laying down. If you fall asleep within 5 minutes of lying down, you probably have severe sleep debt. A person with zero sleep debt may lie in bed 15-20 minutes with a clear mind before actually falling asleep.

Unlike most people today, a person with zero sleep debt will not feel tired throughout the day and will feel little need to sleep until night arrives.

How do I get rid of my sleep debt?

A large sleep debt does not go away spontaneously and it can only be reduced by getting extra sleep. The amount of sleep people need per night varies from person to person, but it's useful to say most teenage and college-age people need something on the order of 8 hours and 30 minutes of sleep per night. Needing less than 7 or more than 10 hours would be rare

The best way to eliminate sleep debt is to consistently sleep more than your daily sleep need every night. Note that you probably will not be able to sleep through an entire weekend to pay of your sleep debt because your biological clock tends to wake you up eventually during the daytime ­ even when you have a large sleep debt.

The maximum amount of sleep debt a person can carry around before collapsing is somewhere between 30-50 hours. I've kept a log of my sleep each night at school this year. Assuming I need the average amount of 8 hours and 30 minutes of sleep each night, I've succeeded in eliminating about 18 hours of sleep debt. I can say I feel much more rested during the day now and that I have enjoyed the long hours I spend in bed.

Who wouldn't like paying off debts while you sleep?

I have made some generalizations in this article. If you would like to learn more about sleep debt and sleep science in general, I recommend I recommend reading "The Promise of Sleep: A Pioneer in Sleep Medicine Explores the Vital Connection Between Health, Happiness, and a Good Night's Sleep," by Dr. William C. Dement, my professor in Sleep and Dreams. Dr. Dement has studied diverse aspects of sleep and dream science for more than 50 years, discovering and naming the five stages of sleep scientists recognize today.