Effects of melatonin and propranolol on sleep of the rat.

Melatonin and L-propranolol, which inhibits melatonin synthesis, were administered to rats at 07.45 h and 19.45 h. Melatonin given in the morning decreased non-REM sleep, but when given at night had no effect on sleep stages. L-propranolol given in the morning had no effect on non-REM sleep, but increased it at night. L-propranolol produced decreased in percentage REM sleep at both times.