The Relationship between Self-reported Restless Sleep and Objectively Measured Physical Activity in Adults with Knee Osteoarthritis.

OBJECTIVE: Despite many health benefits of physical activity, inactivity is endemic among adults with knee osteoarthritis (KOA). Because sleep quality may be a target to improve physical activity behavior, we investigated the cross-sectional relationship between restless sleep and physical activity in participants with or at risk for KOA.

METHODS: We analyzed accelerometer-measured physical activity and clinical data from Osteoarthritis Initiative (OAI) participants. We used multiple regression analysis to evaluate physical activity for participants grouped by the reported frequency of restless sleep adjusting for demographic and medical confounders.

RESULTS: Of the 1892 OAI participants with complete data, 300 (16%) reported restless sleep 3 or more days in the past week. Participants reporting much (3-4 days/week) and most (5-7 days/week) restless sleep had 11.9% and 23.7% less weekly minutes of moderate-vigorous activity, respectively, compared to participants reporting rare restless sleep (less than 1 day/week) (p for trend 0.021). These differences persisted after accounting for age, gender, race, body mass index, medical comorbidity, KOA severity and pain (p for trend 0.023). Differences related to restless sleep were largely attenuated by the presence of high depressive symptoms and low energy levels.

CONCLUSION: Poor sleep quality is associated with less physical activity in persons with or at risk for KOA. Future studies are needed to determine the mechanisms of how poor sleep and physical activity are related, how energy and depression mediate these relationships, and whether interventions that improve sleep quality might result in increased physical activity. This article is protected by copyright. All rights reserved.