Obstructive Sleep Apnea Syndrome (osas) Is a Disorder in Which People Repetitively Stop Breathing during Sleep and Have the Night Time Consequences of Hypoxemia and Sleep

OBSTRUCTIVE SLEEP APNEA SYNDROME (OSAS) IS A DISORDER IN WHICH PEOPLE REPETITIVELY STOP BREATHING DURING SLEEP AND HAVE THE NIGHT TIME CONSEQUENCES OF HYPOXEMIA AND SLEEP FRAGMENTATION, and the daytime consequences of sleepiness and cardiovascular comorbidity.1 OSAS which was once thought to be very rare in females, is actually common in them. In an accompanying review,2 we discuss gender-related differences in clinical presentation and polysomnography. Epidemiologic studies have reported that OSAS affects about four percent of adult males and two percent of adult females.2,3 This difference in prevalence suggests that the female gender may reduce the risk of sleep breathing disorders in adults. In addition, most large series have shown that episodes of apnea in females are less frequent and may be clustered in rapid-eye movement (REM sleep).4 The upper-airway resistance syndrome (UARS), which results from cyclic increases in upper airway resistance leading to brief arousals and daytime sleepiness,5 may be a more common problem in females than males.6 Here we review the mechanisms that could explain gender differences in OSAS which can be divided into several separate but interacting categories: obesity pattern and fat distribution; upper-airway anatomy and function; the control of breathing; and hormone status.7,8