Swanson CM, Shea SA, Kohrt WM, et al. - Researchers investigated if women exposed to the combination of sleep restriction with circadian disruption (SRCD) exhibit an uncoupling of bone turnover markers (BTMs), as previously reported in men. They measured four bone biomarkers (N-terminal propeptide of type I procollagen [P1NP] and osteocalcin = bone formation; C-telopeptide = bone resorption; sclerostin = bone formation inhibitor) in bihourly samples over 24-h at baseline and after ~3 weeks of sleep restriction (~5.6h sleep/24h) with concurrent circadian disruption (SRCD, recurring 28-h ‘day’ in dim light). They assessed five young women (22 ± 2.8 years) and four older women (58 ± 1.8 years) and identified no differences in baseline bone biomarker levels by age. The data gained were in line with prior findings in men and indicate that in women, SRCD negatively affects bone metabolism by reducing markers of bone formation and increasing a marker of bone resorption in young women. If sustained, this pattern of BTM uncoupling may result in bone loss and lower bone mineral density.