Sleep Debt Hard to Repay

Recovery From Chronic Sleep Loss Takes More Than a Good Night’s Sleep

Medically Reviewed by Louise Chang, MD on January 15, 2010

Jan. 15, 2010 -- Bouncing back from a few too many late nights may take more than just sleeping in on the weekends.

A new study shows that the effects of long-term sleep deprivation, such as working odd shifts or staying up late studying for exams over several days or weeks, take more than a night or two of good sleep to make up for.

"Many people have a false sense of reassurance that they can quickly recover from a chronic sleep debt with just one or two days of good sleep,” researcher Daniel Cohen, MD, of the division of sleep medicine at Brigham and Women’s Hospital in Boston, says in a news release. “However, the lingering effect of chronic sleep loss causes performance to deteriorate dramatically when these individuals stay awake for an extended period of time, for example when they try to pull an ‘all-nighter.’"

Researchers found that one long night of sleep can temporarily hide the effects of sleep deprivation and restore performance to normal levels in the short term for about six hours after waking. However, performance may worsen the longer the person is awake, and there is an increased risk of fatigue-related errors the longer the person stays awake.

“Individuals who get too little sleep during the work or school week but try to catch up on weekends may not realize that they are accumulating a chronic sleep debt,” researcher Elizabeth Klerman, associate professor in the division of sleep medicine at Brigham and Women’s Hospital, says in the release. "This may lead to a dangerous situation in which individuals do not realize the extent of their sleep deprivation and their vulnerability to sudden sleepiness when they try to drive or work late into the night."

More Than a Good Night’s Sleep

In the study, published in Science Translational Medicine, researchers had nine adults live on a reduced sleep schedule equivalent to 5.6 hours of sleep per 24 hours for three weeks.

The results showed that although most participants caught up on short-term sleep deprivation with one good night of 10 hours sleep, the effects of long-term sleep deprivation persisted.

Those with chronic sleep debts experienced deteriorating performance for each hour spent awake, which made them vulnerable to errors and accidents, especially late at night during hours normally reserved for sleep.

For example, as the sleep debt increased, performance on reaction timing tests worsened at a faster rate for each additional hour spent awake -- even though reaction times were within normal limits immediately after waking up.

Researchers say the results suggest that sleep deprivation affects the brain’s sleep patterns in at least two different ways. One sleep regulatory process builds up over hours spent awake and another accumulates over days or weeks of not getting enough sleep.

Show Sources


Cohen, D. Science Translational Medicine, Jan. 13, 2010; vol 2: p 14ra3.

News release, Brigham and Women’s Hospital.

News release, Science Translational Medicine.

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