All-night polygraphic recordings of 15 healthy aged persons (82.1 ± 4.8 years old) were conducted for 3 consecutive nights. Thirteen young males (20.9 ± 0.8 years old) were used as the control group. Compared with the young adults, the aged subjects showed extraordinary reductions in stages 3 and 4 sleep. In the young adults, the first four rapid eye movement (REM) periods showed progressive increases in length, whereas in the aged subjects, the same REM periods tended to decrease in length. In the young adults, the percentage of REM sleep increased during the second half of the night, whereas that of the aged subjects was fairly uniform throughout the night. The circadian rhythm of REM sleep for the aged persons apparently shifted, with the acrophase occurring during the first half of the night rather than in the early morning hours.