The Association Between Obstructive Sleep Apnea and the Circadian Rest-Activity Rhythm: A Cross-sectional Analysis of the ELSA-Brasil Cohort.

OBJECTIVES: To investigate the potential association between obstructive sleep apnea (OSA) and the circadian rest-activity rhythm. METHODS: Active or retired employees aged 35-74 years from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) were eligible for inclusion. Participants underwent a standardized clinical evaluation, completed sleep questionnaires, performed a home sleep apnea test, and wore a wrist activity monitor for one week. The primary variables used to characterize the circadian rest-activity rhythm were intradaily variability (IV), interdaily stability (IS), relative amplitude (RA), and the circadian function index (CFI). RESULTS: The cohort comprised 1828 participants (56.1% female), with a mean (SD) age of 49.1 (8.2) years. After adjustment for potential confounders, OSA showed no significant associations with any circadian-related variables. However, stratified analyses revealed that higher apnea-hypopnea index (AHI), treated as a continuous variable, was associated with decreased CFI exclusively in females and with decreased daytime activity in the oldest age tertile (-6.41 [-10.64 to -2.17]). Finally, integrative data analysis revealed that an OSA profile characterized by a higher percentage of time with oxygen saturation below 90%, reduced total sleep time, and daytime sleepiness was associated with a pattern of circadian disruption, marked by increased IV, reduced RA, and diminished IS. CONCLUSIONS: These findings suggest that the association between OSA and the circadian rest-activity rhythm is shaped by both patient-specific characteristics and disease-related factors, highlighting the importance of a patient-centered approach to managing potential circadian disruption in this context.