As reviewed by Zarcone (1973), ethanol and cannabis are also known to produce similar effects on sleep. Acute ethanol and THC administration reduces REM sleep early in the evening with a compensatory rebound occurring later in the night. These effects are probably due to acute tolerance to drug effects and/or elimination in the case of ethanol over the course of the evening. However, the depressive effects on REM sleep are attenuated with repeated administration of either marijuana or ethanol. The synergistic effects of acute ethanol and cannabinoids on sleep have also been observed in rodents where co-administration of ethanol with THC increases sleep time beyond that observed with either drug alone (Friedman and Gershon, 1974; Phillips et al., 1971). The effects of chronic ethanol and cannabis use differ, however. Chronic alcoholic patients experience a significant reduction or even an absence of deep-stage slow-wave sleep and an increase in REM following cessation of ethanol use, while chronic cannabis users show an increase in time spent in REM sleep. In the case of alcoholic patients, the alterations in sleep architecture seem to
