You can't always catch up from sleep loss

BOSTON, Jan. 14 (UPI) -- A good night's sleep cannot make up for chronic sleep deprivation, which has a snowball effect hurting a person's ability to stay alert, Boston researchers say.

People may think they're OK because their body's daily circadian rhythm hides the effects of chronic sleep loss, the study in Science Translational Medicine journal says.

But after sleeping six hours a night for two to three weeks, people's motor skills, reaction times, capacities to focus and other abilities are 10 times worse than after staying awake a single night, Harvard Medical School neurologist and sleep medicine specialist Daniel Cohen said.

The study is "almost scary" because it shows that a large societal segment, including doctors, paramedics, police officers and truckers, "may be at high risk of committing catastrophic errors, particularly in the middle of the night and the early morning hours," University of Chicago sleep researcher Eve Van Cauter tells USA Today.

The study at Boston's Brigham and Women's Hospital looked at the number of consecutive hours study participants were awake, their number of days or weeks of chronic sleep deprivation and how they reacted at different times of day -- three factors combined that determine how well people perform, the researchers say.

The research suggests "it takes longer to recover from sleep debts than has been believed," University of Pennsylvania sleep studies Professor David Dinges tells the newspaper.

It also shows people's sleep regulation is actually at least two separate processes acting on different time scales -- a short-term process causing performance to decline with each hour awake and a long-term component building over weeks of too-little sleep.

The short-term process can be rapidly overcome with a good night's sleep. The researchers say they don't know how many nights of good sleep it takes to recover from the longer-term component.