Sleep Apnea Can Cause Brain Dysfunction by Reducing Oxygen Flow

Fourteen men in a recent study were asked to place small pegs into a board, recall lists of numbers and copy designs on pieces of paper.

All of the men suffer from sleep apnea, a disorder that caused them to wake repeatedly during the night, starved for oxygen and with air passageways blocked.

None of them could complete the tasks as well as a control group of men who suffer from other problems that prevented them from getting a good night’s sleep.

“That indicates there is something more here than just sleep deprivation,” said Robert K. Watson, director of the New Haven Sleep Disorders Center in Connecticut, who conducted the study.

“Losing a couple of nights sleep does not lead to much impairment, but apnea may,” he said. “This may be the first evidence of brain dysfunction.”

Watson’s research is some of the most recent in an effort to determine how lack of sleep affects people’s lives, doctors said.

“We know people are able to perform well on stimulating tasks when they have been deprived of sleep, but have problems on boring or repetitive tasks,” said Dr. George S. Howard, a neurologist and director of the sleep disorders clinic at Boston University.

“There have been studies to find the mechanisms--what biochemical changes occur in the body--but the results are not clear,” he said.

Doctors said it is important to differentiate between sleep apnea, a chronic and potentially life-threatening disorder, and simply losing a few nights of sleep.

In apnea, the brain is deprived of oxygen periodically as airway passages become blocked, Watson said. The patient will awaken momentarily in order to start breathing again, then drift back into sleep.

Watson said his studies showed a real impairment in concentration, memory and psychomotor skills in people with apnea that was not seen in people who had simply been deprived of sleep.

Can Lower IQ

“It’s not clear what the cause might be,” he said. “Some chronic lung diseases show similar types of impairment. It might be due to a reduction of oxygen to the brain.”

Watson estimated that sleep apnea may lower a patient’s IQ approximately 10%.

Normally, people sleep between seven and eight hours out of every 24, although individuals may need more or less, doctors said. When deprived of sleep for a cycle, they function well--as long as the work is stimulating.

If they are deprived of sleep for several days, they may have trouble with such tasks as driving or operating machinery, but they can still rise to the occasion if necessary.

“You look at doctors saving lives even though they haven’t had any sleep,” Howard said.

People who have been deprived of sleep for long periods of time tend to fall into “microsleep,” and nod off for short periods.

Effect of Stimulants

Studies have also shown that stimulants, such as amphetamines and caffeine, have less and less of an effect on people who have gone without sleep for long periods.

“There comes a point where you just can’t keep them awake any longer,” Howard said. “There is a teen-ager who holds the record. He went without sleep for something like two weeks with no ill effects, but that’s an exception.”

People who are psychologically unstable, such as prisoners of war who are being tortured, may suffer from hallucinations and psychotic episodes if they are deprived of sleep over extended periods, he said.

“For those people, sleep deprivation can be traumatic,” he said.

Alan Rechtschaffen, professor of psychology at the University of Chicago, found that prolonged sleep deprivation killed rats in laboratory experiments.

‘Very Long Period’

“It took anywhere from one to five weeks,” he said. “It was a very long period.”

The researcher also found that the rats’ metabolism increased as sleep decreased, even though they were not particularly active. He said he hopes to discover the biochemical changes that cause the increased metabolism and death.

As for humans under normal circumstances, doctors said, they will eventually find some way to get some sleep.

“You won’t recoup an hour of sleep for every hour lost, but there’s no question you’ll sleep longer and more deeply than normal the next cycle,” Howard said. “That’s known as ‘catching up.’ ”