Dose dependent inhibition of REM sleep in normal volunteers by biperiden, a muscarinic antagonist

We tested the effect of biperiden (2, 4, and 8 mg per os 30 min before bedtime) on the polygraphically recorded sleep of normal volunteers ( n = 8). Biperiden is a cholinergic, muscarinic receptor antagonist that may preferentially block the M 1 receptor subtype. Compared with placebo, biperiden significantly prolonged rapid eye movement (REM) latency and suppressed REM sleep time and REM percentage in a dose-dependent manner. These REM suppressing effects of biperiden are similar to those previously reported with scopolamine and other nonselective muscarinic receptor antagonists. Because of uncertainties about the pharmacological specificity of biperiden, further studies are needed to determine the mechanism of action and the role of M 1 receptors subtypes in the regulation of REM sleep.