New Study Shows Some Sleep Deprivation Effects are Not Improved by the Stimulant Amphetamine

6/22/2004

From: Kathleen McCann of the American Academy of Sleep Medicine, 708-492-0930 or kmccann@aasmnet.org

WESTCHESTER, Ill., June 22 -- For individuals required to undergo sleep deprivation in potentially life- threatening situations, a recent series of animal studies by University of Wisconsin-Madison researchers offers important news.

Animals deprived of rapid eye-movement (REM) sleep for up to five days were less able to cope with stressful or threatening situations - and giving them amphetamines to decrease their sleepiness did nothing to improve poor coping responses and, in some cases, actually made them worse.

The research, conducted by University of Wisconsin psychiatry and HealthEmotions Research Institute faculty, was published in the June 15, 2004, issue of the journal SLEEP. The study was also presented June 9, 2004, at the 18th annual meeting of the Associated Professional Sleep Societies in Philadelphia.

Sleep deprivation is quite common in American society, and it is linked to both poor health and increased rates of errors and accidents. Because sleep deprivation is inevitable in some situations (such as disaster rescue, medical and other emergency operations), recent research has focused on measuring how it affects behavior, learning, memory and mood and on developing ways to reduce ill effects from sleep loss.

The UW study was designed to assess the effects of REM sleep deprivation on the performance of rats by measuring certain behaviors they typically show in response to threatening or stressful situations. There has been little scientific attention paid to understanding the role of sleep in coping responses. Rats that are threatened may normally respond passively (by avoiding open parts of a maze or the center of an enclosure, or by "freezing" all body movements) or actively (by burying a threatening object). Measuring these various responses to noxious stimuli or dangerous situations can assess increased fear or anxiety.

"We looked carefully at a number of behaviors in rats that were not sleep-deprived as well as those who were," said Ruth Benca, MD, PhD, lead author of the study. "We found that sleep deprivation interfered with the normal responses the animals used to cope with threats, making them appear as if they were less fearful and more risk-taking. Simply put, the sleep-deprived animals behaved as if the situation were less dangerous than it was.

"Sleep deprivation is well-known to produce performance difficulties in humans and animals. These findings extend the scientific understanding of performance to coping behaviors in potentially lethal situations. They suggest that the combination of decreased caution and decreased coping performance during sleep deprivation could heighten risk in such dangerous situations."

To combat sleepiness and attempt to reduce the negative impact of sleep deprivation, people who are required to stay alert for long periods of time (often in stressful environments) are commonly prescribed the stimulant amphetamine. In the second part of the study, the UW team looked at whether the abnormal behavior demonstrated after sleep deprivation could be reversed if the animals were given amphetamine. To their surprise, amphetamine did not correct the impairments resulting from sleep loss.

"These findings are provocative, but not yet definitive for humans coping with sleep loss," said Benca. "While certain stimulant medications are very important and useful in the treatment of some disorders, they do not help restore the ability to respond to stress; it's still important to sleep. Future research is vital because these data suggest combining sleep deprivation and amphetamine use might have the potential for promoting careless behavior under stress."

The finding is of particular potential significance for adolescents, notes Benca.

"Sleep deprivation is endemic among adolescents, and stimulant use for problems such as attention-deficit hyperactivity disorder is not uncommon," she notes. "We need to find out much more about how sleep deprivation and amphetamine use combine to affect behavior, particularly risk-taking in adolescents."

The study was funded in part by the U.S. Department of Defense.