Researchers have found that sleep loss mimics some of the effects of aging, suggesting that sleep loss may increase the severity of age-related diseases, such as obesity, diabetes and hypertension.

Other research has shown that getting enough sleep makes people more alert, productive and puts them in a better mood.

When a person is tired or sleep deprived, the brain tries to go to sleep. Tired adults are more likely to drift off while driving a car.

Most people need between seven and nine hours of sleep a night, yet most are getting less.

Those people who get less sleep than the body needs build what experts call sleep debt. The debt accumulates over time and takes a toll on people's motor and intellectual functions. Even a little sleep debt can affect people. If there is a sleep debt of 10 hours or more, performance will be impaired.

For optimal functioning, it is best to get enough sleep every night. If that is not possible, experts say you should try to make up for sleep loss as soon as possible.

Nanci Hellmich, "If not snoozing, you're losing" USA Today, March 23, 2000, 9D