Comparison of two muscle relaxant drugs on human sleep: diazepam and parachlorophenylgaba

The effects of two muscle relaxant drugs of different chemical structures, parachlorophenylgaba and diazepam, were investigated in the sleep of normal young adults. Parachlorophenylgaba did not show any significant and dose-related effect. In contrast, diazepam induced clear modifications, including a decrease of stage 4 and of REM-sleep, an increase of spindles and a decrease of K potentials in stage 2, a decrease of rapid eye movements in REM-sleep, and finally a decrease of body movements. In addition, the recovery of REM-sleep upon withdrawal of the drug was much faster than the recovery of stage 4. These results add a new contribution to known differences in the pharmacological profiles of these two compounds ; for diazepam, the possible role of GABA mediated monoaminergic mechanisms is discussed.