Objective:To investigate the effects of chronic sleep deprivation (CSD) on bone microstructure and peak bone mass (PBM) in SD rats.Methods: Twenty-four SD rats were randomly divided into CSD group and control group. In the CSD group, a CSD model was established using a new sleep deprivation instrument for rats and mice, and intervened for 5 weeks. Bone tover markers including P1NP and CTX-1 before and after the experiment were observed. After the experiment, the left femur were scanned by Micro-CT, and the cortical bone and bone trabecula were three-dimensionally reconstructed, respectively. The bone mineral density (BMD) and relevant parameters were detected.Results: CT images of the femur (proximal ends) showed significant trabecular loss in CSD rats. Trabecular parameters including bone volume fraction (BV/TV), trabecular number (Tb.N) and trabecular separation (Tb.Sp) in the CSD group were all lower than those in the control group. The bone cortex of the middle segment of the femur and tibia in CSD rats was also lower than that in the control group. The parameters of bone cortex including total tissue area (Tt.Ar), cortical bone area (Ct.Ar) and cortical bone thickness (Ct.Th) in the CSD group were significantly lower than those in the control group (P < 0.01). After chronic CSD, BMD of both bone trabecula and bone cortex of the femur was lower, while the corresponding P1NP and CTX-1 were significantly higher than those in the control group.Conclusion: Sleep plays an important role in PBM formation. CSD accelerates bone tover and thus significantly reducing PBM in SD rats.