Controllability and duration of stress alter central nervous system depressant-induced sleep time in rats.

Rats were exposed to either 80 escapable shocks or yoked inescapable shocks and then injected with several hypnotic doses of sodium pentobarbital, midazolam, or ethanol; their sleep-time duration was compared with that of naive controls. Inescapable shock exposure resulted in a significant increase in ethanol-induced sleep time compared with the escapable shock and naive control groups. Both escape and yoked groups showed an increase in barbiturate-induced sleep time compared with controls, although no difference was observed for midazolam. Acute stress (20 5-sec inescapable shocks) did not alter the depressant-induced sleep time for any of the drugs tested. These results illustrate the importance of psychological aspects of stress and its influence on the potency of certain depressants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)