Influence of sex and age on duration and frequency of sleep apnea events.

OBJECTIVES: Differences between men and women potentially provide insight into the regulation sleep apnea events. This study, therefore, examined how apnea frequency and duration varied according to age, sex, and sleep stage in a clinical population.

DESIGN: NA SETTING: NA PATIENTS: Patients were 215 women and 215 men referred to a sleep disorders center with symptoms of obstructive sleep apnea and matched for BMI. Apnea events were compared across three age groups (18-39, 40-59, and 60-88 years) in stage 2 and in REM sleep.

INTERVENTIONS: NA RESULTS: In stage 2 sleep, young and middle aged women were similar averaging 15 and 13 apnea events per hour respectively. Men had significantly more events averaging 27 and 30 events per hour for the corresponding age groups. The apnea frequency doubled from middle age to older women, and the sex difference narrowed between the older males and females to a non significant difference (26 events per hour for women versus 34 events per hour for men). Apnea duration was significantly longer in men than in women. Stage 2 apnea duration increased significantly with age for men (20.1, 21.5, 23.8 s) and women (16.7, 18.3, 20.6 s) across the three age groups. This also occurred in REM sleep in for men (22.8, 26.5, 29.8 s) and women (19.3, 22.4, 26.6 s).

CONCLUSIONS: Duration did not demonstrate the marked "menopausal effect" that there was for apnea frequency. Female gender and younger age conferred benefit primarily by preventing airway collapse (reduced apnea frequency) with less of an effect on apnea duration, i.e., the ability to end the apnea. Compared to stage 2 sleep, REM sleep reduced the differences between men and women in apnea frequency. One explanation may be that differences in muscle tone of the upper airway account for the sex differences in apnea frequency.