Study objectives: To examine the influence of chronic time-in-bed (TIB) restriction on selected health-related outcome variables in older long sleepers.
Design: Randomized, controlled trial.
Setting: Home-based.
Participants: Forty-two older adults (aged 50-70 y) who reported sleeping at least 8.5 hours. Following extensive screening, participants were assessed for 10 weeks.
Intervention: During a two-week baseline, participants followed their usual sleep-wake habits. Participants were then randomized to one of two eight-week treatments: (1) TIB restriction, in which participants were asked to follow a fixed sleep schedule with a TIB of 90 minutes less than recorded during baseline or (2) a control treatment, which involved following a fixed sleep schedule (consistent with average baseline) but no TIB restriction.
Measurements and results: Continuous wrist actigraphic sleep estimation indicated that TIB restriction elicited significant reductions in TIB and total sleep time compared with the control treatment and significant (albeit modest) improvements in sleep efficiency and sleep latency. However, compared with the control treatment, TIB restriction elicited no significant change in depression, sleepiness, health-related quality of life, or neurobehavioral performance. Moreover, follow-up assessments for one year indicated that, after completing the experiment, the participants assigned to TIB restriction continued to restrict their TIB (at their own initiative) by an average of approximately one hour.
Conclusions: The results suggest good tolerance of chronic moderate TIB restriction, without detrimental effects, among older long sleepers.