IT HAS BEEN shown in many publications1,2 that there are two types of sleep: orthodox or nondreaming sleep and rapid eye movement (REM) or dreaming sleep. The description of these two separate physiological states and the finding that barbiturates have a profound and long-lasting effect on REM sleep3 gave impetus to many recent studies of the effects of drugs on sleep. It has been found that hypnotics,3-5 meprobamate,6 and alcohol7 cause an immediate decrease in REM sleep. With continued administration, tolerance develops so that REM sleep values return to normal. On withdrawal, there is an immediate overswing or "rebound" in REM sleep taking several weeks,3 even from small doses4 of the drug, to return to predrug levels.
During some drug withdrawal syndromes, there is an excess of REM sleep. This is true of both alcohol withdrawal8,9 and barbiturate withdrawal.10 In the initial withdrawal period a frequent clinical complaint is what the alcoholic calls "night terrors" and the studies by Greenberg