Chronic sleep loss hampers performance

Wed Jan 13, 2010 4:44pm EST
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By JoAnne Allen

WASHINGTON (Reuters) - One night of good sleep is not enough to recover from chronic sleep deficit, which over time hinders a person's ability to stay alert and attentive, U.S. researchers said on Wednesday.

Many nights of too little sleep when the body's rhythm says it is time to snooze have cumulative detrimental effects on how a person performs and could be a safety risk, the researchers wrote in the journal Science Translational Medicine.

"Insufficient sleep over multiple sleep-wake cycles causes performance to deteriorate much faster for every additional hour we spend awake, particularly during the biological night," lead author Dr. Daniel Cohen of Brigham and Women's Hospital in Boston said in a telephone interview.

On average, a person needs about eight hours a night to preserve performance, said Cohen, a neurologist. Acute sleep loss is being awake for more than 24 hours in a row and chronic sleep loss is getting only about four to seven hours of sleep per night, he said.

Cohen's team tracked nine healthy volunteers -- five men and four women -- to see what effect a combination of acute sleep loss, chronic sleep loss and biological sleep rhythm might have on their ability to function.

The researchers found that while most participants caught up on acute sleep loss with a single night of 10 hours sleep, those with chronic sleep loss showed deteriorating performance for each hour spent awake.

The volunteers were kept in a hospital for 38 days and lived on various sleep cycles. They were tested every four hours to measure alertness and attentiveness.

Cohen said researchers know that three days is not enough to recover from chronic sleep loss, but they still do not know how many days or weeks may be needed.   Continued...

<p>A man sleeps on a bed put out for attendees of the 5th World Meeting of Families July 7, 2006 at the Valencia fairgrounds one day ahead of Pope Benedict XVI's visit to Spain. REUTERS/Victor Fraile</p>