Fig. 2: Observational association of sleep duration with fracture risk using a restricted cubic spline based on model 0 based on different cut points.

a Sleeping 7 h per day and b sleeping 8 h per day. Hazard ratios are indicated by blue solid lines and the 95% confidence intervals by blue shaded areas. The red line denotes the harzard ratio of one. In all these analyses, models were adjusted for risk factors for fracture, including age, sex, body mass index, education, smoking, alcohol consumption, physical activity, cognitive impairment, depression, and the use of glucocorticoid medication, benzodiazepines, and antidepressants.