No effect of 8-week time in bed restriction on glucose tolerance in older long sleepers.
The aim of this study was to investigate the effects of 8 weeks of moderate restriction of time in bed (TIB) on glucose tolerance and insulin sensitivity in healthy older self-reported long sleepers. Forty-two older adults (ages 50-70 years) who reported average sleep durations of >or=8.5 h per night were assessed. Following a 2-week baseline, participants were randomly assigned to two 8-week treatments: either (i) TIB restriction (n = 22), which involved following a fixed sleep schedule in which time in bed was reduced by 90 min compared with baseline; (ii) a control (n = 18), which involved following a fixed sleep schedule but no imposed change of TIB. Sleep was monitored continuously via wrist actigraphy recordings, supplemented with a daily diary. Glucose tolerance and insulin sensitivity were assessed before and following the treatments. Compared with the control treatment, TIB restriction resulted in a significantly greater reduction of nocturnal TIB (1.39 +/- 0.40 h versus 0.14 +/- 0.26 h), nocturnal total sleep time (TST) (1.03 +/- 0.53 h versus 0.40 +/- 0.42 h), and 24-h TST (1.03 +/- 0.53 h versus 0.33 +/- 0.43 h) from baseline values. However, no significant effect of TIB restriction was found for glucose tolerance or insulin sensitivity. These results suggest that healthy older long sleepers can tolerate 8 weeks of moderate TIB restriction without impairments in glucose tolerance or insulin sensitivity.
Zielinski
Mark R
MR
Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA.
Kline
Christopher E
CE
Kripke
Daniel F
DF
Bogan
Richard K
RK
Youngstedt
Shawn D
SD
D000368:Aged; D015992:Body Mass Index; D006970:Disorders of Excessive Somnolence / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D017286:Polysomnography; D012720:Severity of Illness Index; D012892:Sleep Deprivation / Q000453:epidemiology; D011795:Surveys and Questionnaires