Bone turnover is altered during 72h of sleep restriction: a controlled laboratory study

PurposeThe objective of the study was to evaluate how controlled, short-term sleep restriction (SR; 72h) alters markers of bone formation and resorption and urinary calcium (Ca) output.MethodsTen healthy, sleep-adequate, male soldiers were housed in the research facility one day prior to and for the duration of SR. Diet was controlled to provide adequate energy balance and macronutrient distribution, meeting the recommended dietary allowance (RDA) for Ca. Subjects engaged in light activities to maintain wakefulness and were allowed 2h of sleep per night (0430-0630 hours). Blood samples were collected each morning at 0h (baseline) and 24, 48, and 72h of SR. Serum was assayed for parathyroid hormone (PTH), bone alkaline phosphatase (BAP), tartrate-resistant acid phosphatase (TRAP), and C-terminal telopeptide of type I collagen (CTX). Urine was collected in 24h increments during SR for measurement of Ca and creatinine (Cr).ResultsBAP was reduced at 24h (P=0.015) and resorption markers TRAP and CTX were increased after 48 and 72h of SR compared to baseline (P<0.05). The ratio of BAP:TRAP was significantly lower (P=0.017) at 48 and 72h of SR. In contrast, total 24h urinary Ca and Ca/Cr excretion were unchanged.ConclusionsMarkers of bone formation and resorption are uncoupled in response to as little as 48h of SR even when Ca intake is at the RDA. Sleep deprivation may be a risk factor for reduced bone health due to perturbations in bone turnover.