Nocturnal sleep in squirrel monkeys.

Abstract The nocturnal sleep records of three squirrel monkeys over 12 h sessions were examined for 7 consecutive nights. The sleep records were described in terms of the percentage of time in each of the stages of Awake. Stages 1.2.3 4 and REM. The mean percent time spent in sleep was 82.4″ ″ of the recording period. The average amount of ″ ″ REM sleep was 22.9″, with a total NREM of 58.8″ ″ . The presence of 3 4 (slow wave) sleep was largely restricted to the first half of the nightly session with REM sleep the dominant stage in the second half of the night. Comparison of the sleep of the squirrel monkey with other primates higher on the phytogenetic scale indicated the squirrel monkey would serve as an excellent representative for the study of primate sleep wakefulness.