Chronic Moderate Sleep Restriction in Older Adults (MSSS)

• Change in adherence to sleep restriction from baseline [ Time Frame: Daily for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of ability to adhere to a 60 min time-in-bed restriction over 12 weeks
  
  

• Change in sleepiness from baseline [ Time Frame: Every week for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of sleepiness by weekly self-report for 12 weeks
  
  
• Change in health functioning from baseline [ Time Frame: Every 2 weeks for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of health functioning by self-report for 12 weeks
  
  
• Change in sleep quality from baseline [ Time Frame: Every month for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of sleep quality by self report every month for 12 weeks
  
  
• Change in measures of cognitive performance from baseline [ Time Frame: Every month for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of cognitive performance including standardized tasks to assess attention every month for 12 weeks
  
  
• Change in physical activity from baseline [ Time Frame: Every 8 weeks for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of physical activity by waist actigraphy and self-report every 8 weeks for 12 weeks
  
  
• Markers of glucose metabolism [ Time Frame: Baseline and at 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of glucose metabolism by fasting glucose, glucose tolerance test, and hemoglobin A1C at baseline and again at 12 weeks
  
  
• Change in depressive symptoms from baseline [ Time Frame: Every 2 weeks for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of depressive symptoms by self-report every 2 weeks for 12 weeks
  
  
• Markers of inflammation [ Time Frame: Baseline and at 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of cellular and genomic markers of inflammation at baseline and at 12 weeks
  
  
• Change in fatigue from baseline [ Time Frame: Every 2 weeks for 12 weeks ] [ Designated as safety issue: No ]
  Evaluation of fatigue by self-report every 2 weeks for 12 weeks
  
  

Epidemiologic studies have consistently shown that self -reported sleep durations of <7 hr and >8 hr are associated with increased mortality and morbidity. The risks associated with short sleep are consistent with a vast experimental literature indicating detrimental effects of profound sleep restriction. However, there has been little study of chronic moderate sleep restriction, which is far more common, and thus more important from a public health standpoint. The risks associated with long sleep have scarcely been experimentally examined, though epidemiological data suggest sleep restriction might promote health/longevity in long sleepers. Older adults might be more vulnerable than young adults to negative effects of further sleep impairment, perhaps particularly via inflammatory mechanisms. Negative effects might be at least as evident in long sleepers as in average sleepers if long sleep reflects underlying morbidity, as many have posited. On the other hand, older adults might tolerate (or benefit) from moderate sleep restriction. Older adults often tend to spend excessive time in bed (TIB), particularly long sleepers, and extra TIB could contribute to age-related sleep fragmentation and morbidity, which could be ameliorated with modest TIB restriction. The aims of this study 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 12 weeks of 60 min TIB restriction on health-related measures in older long vs. average sleepers. One hundred older adults (ages 60-80 yr) who report sleeping 8-9 hr per night and 100 adults of the same age range who report sleeping 6-7.25 hr per night will be examined at 4 experimental sites over 5 years. Following a 2-week baseline, participants will be randomly assigned to one of two 12-week treatment groups. (1) A sleep restriction group (n=60 long sleepers and n=60 average sleepers) will be assigned to a fixed sleep- wake schedule, in which time in bed is reduced precisely 60 min below each participant's baseline time in bed (TIB). (2) A control group (n=40 long sleepers and n=40 average sleepers) will have no sleep restriction, but will also follow a fixed sleep schedule. Sleep will be assessed continuously with actigraphy and a daily diary. Questionnaires will be answered. Measures will include body weight, glucose tolerance, sleepiness, depression, quality of life, psychomotor vigilance, incidence of automobile accidents, incidence of illness, and multiple markers of inflammation. Physical exams during weeks 2 and 6 of the intervention and a study ombudsman will further monitor potential adverse effects. Follow-up assessments will be conducted for 12 months. The proposed clinical trial will provide the most comprehensive Phase 1 assessment of risks and benefits of chronic moderate TIB restriction ever conducted.