Arousal episodes during sleep in the neonatal rat

Hippocampal EEG and neck EMG activity were recorded in restrained as well as in unrestrained rat pups following treatment with drugs which selectively suppress wakefulness and active sleep, respectively. Chloral hydrate did not affect active sleep but eliminated the bursts of coordinated total-body movements which were seen during sleep, especially under conditions of restraint. Chlorimipramine, in contrast, suppressed active sleep while sparing the coordinated total-body motility. It is concluded that these latter movements represent an episodic arousal phenomenon, against a background of quiet sleep, which becomes intensified under certain postural conditions.