Obstructive sleep apnea may induce sleep–wake cycle dysregulation: An actigraphic study

Obstructive sleep apnea (OSA) causes sleep fragmentation and excessive daytime sleepiness (EDS). OSA has been hypothesised to impair the circadian sleep-wake rhythm, and this dysregulation may in turn exacerbate OSA-related diurnal symptoms. Hence, this study aimed to assess the sleep-wake rhythm through actigraphy, and its relationship with EDS in patients with untreated OSA. Patients with moderate-severe OSA (apnea-hypopnea index ≥15/h) and healthy controls (HC) underwent a 7-day actigraphic recording to evaluate the sleep-wake rhythm. Participants underwent a sleep medicine visit and completed the self-report questionnaires assessing EDS (Epworth sleepiness scale, ESS), sleep quality (Pittsburgh sleep quality index, PSQI), and chronotype (morningness-eveningness questionnaire, MEQ). This study included 48 OSA patients (72.9% males; mean age 56.48 ± 9.53 years), and 22 HC (45.5% males; mean age 53.73 ± 18.20 years). After controlling for MEQ scores, actigraphic recording showed that the OSA patients present a lower sleep time (p = 0.011) and sleep efficiency (p = 0.013), as well as a higher sleep latency (p = 0.047), and sleep fragmentation (p = 0.029) than the HC. Regarding the sleep-wake rhythm actigraphic parameters, the OSA patients showed a lower average activity during the most active 10-hour period (p = 0.036) and a lower day/night activity ratio (p = 0.007) than the HC. Patients with OSA also reported higher ESS (p = 0.005) and PSQI scores (p < 0.001), and a chronotype less of morning type (p = 0.027) than the HC. In conclusion, this study documented a reduced diurnal motor activity and lower day/night activity ratio in OSA patients than in controls. These findings suggest a dysregulation of the circadian sleep-wake rhythm in OSA, possibly related to both EDS and reduced daytime motor activity.