The effect of naloxone on normal human sleep.

Placebo and naloxone (4, 8, and 12 mg) were infused on separate nights in a double-blind fashion over a 20-min period between the 25th and 45th min of sleep in normal volunteers. Naloxone produced a dose-dependent increase in REM latency (the time from onset of sleep until the first REM period), and duration of the first REM period and second NREM period. The number of REM periods was also reduced.