10 hours of sleep isn't enough to recharge your brain after 5 days of sleep deficit.

DARIEN, Ill. – A study in the Aug. 1 issue of the journal Sleep suggests that a dose of extra sleep on the weekend may be good medicine for adults who repeatedly stay up too late or wake up too early during the workweek. However, even a night of 10 hours in bed may not be enough to cure the negative effects of chronic sleep restriction.

Results show that neurobehavioral impairments such as increased lapses of attention and delayed reaction times accumulated across a period of five days when sleep was restricted to less than four hours per night. Behavioral, subjective and physiological measures of alertness improved significantly after a night of recovery sleep, with larger doses of sleep producing greater gains. Yet some neurobehavioral deficits continued to linger after the maximum recovery dose of 10 hours in bed, during which participants slept for an average of about nine hours. The study suggests that complete recovery from sustained sleep restriction may require even more sleep during one night or multiple nights of extended sleep.

As the researchers point out, the body's circadian rhythm will probably prevent a lot of people from even getting 10 hours. So if you are counting on a single night's sleep to do a full recharge after a long hard week think again.

Brain performance decayed each day over 5 days of insufficient sleep.

Mean total sleep time dropped from 8.47 hours at baseline to 3.72 hours on the first night of sleep restriction. Relative to the control group, sleep restriction degraded all neurobehavioral functions across the five days of sleep loss. One night of recovery sleep then improved all neurobehavioral outcomes as sleep doses increased. However, lapses of attention, subjective sleepiness, reaction times and fatigue scores all remained elevated above baseline levels in the 27 participants who spent 10 hours in bed on the recovery night.

"The additional hour or two of sleep in the morning after a period of chronic partial sleep loss has genuine benefits for continued recovery of behavioral alertness," said Dinges. "The bottom line is that adequate recovery sleep duration is important for coping with the effects of chronic sleep restriction on the brain."

If you are pushing yourself to get a lot done at work and with home responsibilities your productivity could be falling enough to cancel out the additional hours worked.

If you sleep less than 6 hours per night for 2 weeks your performance will be like you didn't sleep for 2 days.

Previous research led by Dinges found that even relatively moderate sleep restriction can seriously impair waking neurobehavioral functions in healthy adults. The study published in the journal Sleep in 2003 found that chronic restriction of sleep to six hours or less per night for 14 consecutive days produced cognitive performance deficits equivalent to up to two nights of total sleep deprivation.

These researchers advise you to cut back on TV to get enough sleep. Hey, I've already done this: A couple of months ago I canceled my cable TV subscription and unplugged the TV. After a few weeks I didn't miss the TV at all. I sleep more too.

In a 2009 study in the journal Sleep, Dinges and Mathias Basner, MD, reported that people who worked eight hours or more woke up earlier in the morning than people who worked less than eight hours, but they did not go to bed earlier at night. The study also found that watching TV was the primary activity people engaged in before going to bed. The authors suggested that giving up some TV viewing in the evening is one strategy to reduce chronic sleep restriction.

Consider the long term health effects of sleep deprivation too. Sleep 5 or fewer hours per day and double your risk of cardiovascular disease.

Results show that eight percent of the study population reported sleeping five hours per day or less including naps, and multivariable logistic regression analysis revealed that their risk of any cardiovascular disease was more than two times higher than that of people who reported a daily sleep duration of seven hours (adjusted odds ratio = 2.20). Nine percent of participants reported sleeping nine hours or more per day, and they also had an elevated risk of cardiovascular disease (adjusted OR = 1.57). Results were adjusted for potential confounders such as age, sex, race, smoking, alcohol consumption, body mass index, physical activity, diabetes, hypertension and depression.