Effect of chronic marijuana administration of stages of primate sleep-wakefulness.

The effects of the repeated administration of delta-9-tetrahydrocannabinol on sleep-wakefulness patterns were studied in adult male squirrel monkeys. The percent time spent in slow wave sleep was reduced with chronic treatment and failed to return to base line levels after 30 days of recovery. The amount of time spent in Stage 1 or drowsy state increased with repeated treatment and remained elevated through recovery. Changes observed in other stages of sleep-wakefulness were sensitive to repeated treatment with marijuana but were found to return to base line levels during recovery.