Effects of chronic sleep deprivation on the bone mineral density, bone microarchitecture and body weight of mice: exploratory study

Objective This study aimed to investigate the long-term effects of chronic sleep deprivation (CSD) on the bone mineral density (BMD), bone microarchitecture, biomechanical properties and body weight of middle-aged and older male C57BL/6 mice. Methods Twenty-one 8-month-old mice were randomly assigned to a CSD group (n = 9) or a control group (n = 12). The CSD group was subjected to sleep deprivation using an automated sleep deprivation apparatus for 3 months. Trabecular bone microarchitecture at the distal femur was evaluated by microcomputed tomography. Femoral biomechanical properties were assessed using a three-point bending test, and body weight was monitored weekly throughout the experiment. Results Three months of CSD significantly reduced BMD, bone volume (BV) and trabecular thickness (Tb.Th) compared with those of the control group (all P < 0.05). Trabecular separation (Tb.Sp) and bone surface (BS) were also significantly decreased ( P < 0.05). No significant differences were observed in trabecular number (Tb.N), bone volume fraction (BV/TV) or other microarchitectural parameters. Three-point bending test showed no statistically significant differences in any biomechanical indices, including maximum load, bending stiffness and elastic modulus (all P > 0.05), between the two groups. Body weight monitoring revealed that the CSD group had significantly lower body weight at the early stage of the experiment (week 1) and at week 8 compared with the controls ( P < 0.05). No significant differences were observed at most other time points, showing a fluctuating pattern with baseline differences. Conclusion Three months of CSD led to decreased BMD and trabecular thinning in middle-aged and older male mice. No significant deterioration of overall bone biomechanical properties was observed, suggesting the presence of compensatory mechanisms in bone. The effect of sleep deprivation on body weight was intermittent rather than sustained. These findings provide experimental evidence for a comprehensive understanding of the relationship between sleep duration and skeletal health.