Effects of two adrenergic beta-receptor blockers on the sleep cycle of the cat.

Sixteen hour polygraphic recordings (EEG, EOG and EMG) were obtained from 14 adult cats after intraperitoneal injections of propranolol (5 mg/kg) or pindolol (0.1 or 0.5 mg/kg). All injections moderately increased waking, which consisted mainly of a sedated drowsy stage. Both drugs also decreased deep slow wave sleep, while light slow wave sleep remained at control levels. The changes were more marked after propranolol, which also significantly reduced paradoxical sleep (PS). The decrease in the deeper stages of sleep and PS is suggested as being due to blockade of the central adrenergic beta-receptors per se and/or antagonistic effects of the beta-blockers on 5-HT receptors. The results agree with the finding that beta-blockers cause insomnia in susceptible patients, but they do not suggest that intensified dreaming or nightmares reported by others are likely to be caused by increased PS.