Age differences in sleep-wake behavior under natural conditions.
Differences in lifestyle may account for a considerable portion of the reported age-related changes in overt circadian rhythmicity. By instructing a group of healthy, noninstitutionalized, elderly subjects and a group of young adults to keep a sleep-wake log for a period of two weeks, and to wear an activity monitor for an overlapping period of 11 days, we attempted to assess age-related differences in the habitual sleep-wake behavior, in particular its day-to-day variability. Four clusters of coherent variables were constructed, reflecting (1) circadian phase, (2) variability of sleep-wake behavior, (3) sleep-wake continuity and (4) subjective sleep-wake quality. The results showed that, in comparison with the young subjects, the elderly had a relatively advanced and more regular sleep-wake pattern, reported more midnight awakening and did not differ in their subjective sleep evaluation. In spite of a greater regularity in their lifestyle (which would favor a larger amplitude of the overt circadian rhythmicity) oral temperature measurements showed some evidence of a weakened 24-h periodicity in the elderly.
Kramer
C J
CJ
Department of Psychonomics, University of Amsterdam, Netherlands.
Kerkhof
G A
GA
Hofman
W F
WF
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D000704:Analysis of Variance; D001831:Body Temperature; D002940:Circadian Rhythm; D003625:Data Collection / Q000379:methods; D001330:Electronic Data Processing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D012890:Sleep; D014851:Wakefulness