Sleep-waking cycle in rabbits after cerebral ischemia.

In rabbits experimental cerebral ischemia of 4-6 min was followed by degradation of the electroencephalographic sleep-waking cycle, as determined from 3 h afternoon records: I. Hyposomnia i.e., reduction of slow wave and paradoxical sleep lasting for about 2 days, was seen, with gradual normalization in case of survival. II. In the first postischemic days abundant 14-17 c/sec spindles appeared in the motor cortex against a low voltage desynchronized background, making the EEG of waking qualitatively different from control records. The results are discussed with reference to polygraphic studies in comatose patients, EEG phenomenology of drowsiness, and cerebral monoamines.