Sex differences in low arousal threshold in obstructive sleep apnea

Background: Obstructive Sleep Apnea Syndrome (OSAS) is the most common sleep-related breathing disorder, considered more prevalent in males. Recent evidences suggest that prevalence of OSAS in females is underestimated, with a clinical phenotype marked by sleep fragmentation, poor sleep quality, and neurobehavioral symptoms. We hypothesized that a low arousal threshold (low AT) may be more common in females, which may underline these clinical and polysomnographic differences. Methods: In this retrospective multicentric study, 84 females and 93 males with OSA underwent a Home Sleep Apnea Test (HSAT) reviewed by a sleep expert. Low AT was predicted using the Edwards score criteria. Results: Out of 177 patients, low AT was identified in 60.7 % of females and 40.9 % of males (p = 0.008). Stratifying by OSA severity, low AT was more prevalent in patients with mild disease, both in females and males. Among obese patients (Body Mass Index, BMI ≥30 kg/m2), low AT was present in 60.9 % of females compared to 24.3 % of males (p = 0.001). Conclusion: Our findings indicate that a low AT is significantly more prevalent in OSA females, remembering that our female population mainly corresponds to post-menopausal females. This may explain the more pronounced sleep fragmentation and neurobehavioral symptoms in women.