Sex differences in low arousal threshold in obstructive sleep apnea

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.

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.

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).

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.