An inadequate amount of poorly timed (daytime) sleep can impair optimal health and are risk factors for metabolic conditions like diabetes and obesity. We were the first to report that an altered sleep schedule (similar to the stresses experienced during rotating shift work) could negatively impact bone health in men by decreasing a marker of bone formation. Over time, less bone formed could lead to bone loss, osteoporosis, and a higher risk of fracture. Women are more commonly affected by osteoporosis than men, however, the effects of altered sleep timing and duration on bone health in women are unknown. This research, made possible by the Center for Women's Health Research, will investigate if the same altered sleep schedule negatively impacts bone health in women, as it does in men. If sleep disruption negatively impacts bone metabolism it could impact women’s health by altering the approach to the prevention, evaluation and treatment of osteoporosis.