Association Between Kyphosis and Sleep Disturbance in Community-Dwelling Older Adults: The Locomotive Syndrome and Health Outcome in Aizu Cohort Study

Purpose: Worsening sagittal alignment of the spine, particularly kyphosis, may cause difficulty in assuming a supine position, restricting sleeping posture and movement and potentially leading to sleep disturbances. However, no studies have explored the relationship between sagittal spinal alignment and sleep disturbance. This study aimed to clarify the relationship between sagittal spinal alignment and sleep disturbance.

Methods: Data were drawn from the Locomotive Syndrome and Health Outcome in Aizu Cohort Study (LOHAS) in 2010. Sleep disturbance was assessed using a self-administered questionnaire on average sleep duration over the past month, with patients classified as having sleep disturbance if they slept for fewer than six hours per day. The sagittal vertical axis (SVA) was measured on standing whole-spine radiographs and classified into three groups based on the Scoliosis Research Society Schwab classification: non-kyphosis: <40 mm; moderate kyphosis: 40-95 mm; and severe kyphosis: >95 mm. Age, sex, drinking habits, depressive symptoms, overactive bladder symptoms, and napping habits were assessed as confounding factors. The association between SVA and sleep disturbance was evaluated using adjusted odds ratios and 95% confidence intervals (CIs).

Results: The percentage of sleep disturbance among the 772 subjects in the analysis was 8.9% for non-kyphosis, 9.1% for moderate kyphosis, and 20.0% for severe kyphosis. Using non-kyphosis as the reference, adjusted odds ratios (ORs; 95% confidence intervals (95% CIs)) were 1.16 (0.65-2.05) for moderate kyphosis and 2.86 (1.13-7.26) for severe kyphosis.

Conclusion: Kyphosis in community-dwelling adults was found to be associated with sleep disturbance. Therefore, it is necessary to focus on the parasomnias of sleep disturbance in patients presenting with spinal kyphosis.