Rotator cuff injury disrupts sleep architecture in mice and exhibits a light-dark phase-dependent pattern

Rotator cuff injury (RCI) is a common musculoskeletal disorder and is frequently accompanied by sleep disturbances. However, objective assessments of sleep architecture alterations in this context remain limited. Here, we established a mouse RCI model to systematically characterize RCI-induced changes in sleep architecture and to provide neurophysiological clues to the mechanisms underlying sleep disruption.

Using a mouse RCI model, we analyzed sleep architecture based on 24-hour EEG/EMG recordings. Mice were assigned to RCI and sham groups, and we quantified vigilance-state durations, the sleep fragmentation index (SFI), episode numbers, and EEG power spectral density (PSD) features over 24 hours as well as across the light (12 h) and dark (12 h) phases. Data were analyzed using unpaired t-tests and two-way repeated-measures ANOVA.

RCI mice exhibited marked disruptions in sleep architecture, characterized by reduced NREM sleep duration, increased wakefulness, and enhanced sleep fragmentation during the light phase, while total REM sleep duration remained largely unchanged. These alterations showed clear light-dark phase dependence, accompanied by significant alterations in stage-specific EEG spectral power. Compared with sham controls, the number of NREM episodes increased in RCI mice, whereas REM episode counts did not differ significantly. The SFI was significantly elevated in the RCI group, indicating impaired sleep continuity and reduced sleep quality.

This study demonstrates that rotator cuff injury disrupts sleep architecture, with a pattern indicative of impaired sleep maintenance and increased sleep fragmentation. These findings provide new neurophysiological evidence linking rotator cuff injury to sleep disturbances and may inform future strategies to alleviate nocturnal sleep problems in patients with rotator cuff pathology.