Abstract
Epidemiologic studies have consistently shown that sleeping <7 h and ≥8 h is associated with increased mortality and morbidity. The risks of short sleep may be consistent with results from experimental sleep deprivation studies. However, there has been little study of chronic moderate sleep restriction and little evaluation of older adults who might be more vulnerable to negative effects of sleep restriction, given their age-related morbidities. Moreover, the risks of long sleep have scarcely been examined experimentally. Moderate sleep restriction might benefit older long sleepers who often spend excessive time in bed (TIB) in contrast to older adults with average sleep patterns. Our aims are: (1) to examine the ability of older long sleepers and older average sleepers to adhere to 60 min TIB restriction; and (2) to contrast effects of chronic TIB restriction in older long vs. average sleepers. Older adults (n = 100) (60-80 years) who sleep 8-9 h per night and 100 older adults who sleep 6-7.25 h per night will be examined at 4 sites over 5 years. Following a 2-week baseline, participants will be randomized to one of two 12-week treatments: (1) a sleep restriction involving a fixed sleep-wake schedule, in which TIB is reduced 60 min below each participant's baseline TIB; and (2) a control treatment involving no sleep restriction, but a fixed sleep schedule. Sleep will be assessed with actigraphy and a diary. Measures will include glucose tolerance, sleepiness, depressive symptoms, quality of life, cognitive performance, incidence of illness or accident, and inflammation.