Respiratory activity of genioglossus. Interaction between alcohol and the menstrual cycle.

Alcohol consistently decreases genioglossal electromyographic (EMG) activity in awake men, but in women this response is more variable, possibly because of the menstrual cycle. To assess the interaction between alcohol and the menstrual cycle on genioglossal EMG activity, we measured ventilation and genioglossal EMG activity in 9 normal women before and after they drank 1 ml/kg alcohol. The effect of alcohol on ventilation and genioglossal EMG activity was studied twice in each subject: once during the follicular phase and again during the luteal phase of the menstrual cycle. Measurements were made while the subjects breathed room air and rebreathed a hypercapnic gas mixture. The ventilatory response to CO2 was significantly greater during the luteal phase of the menstrual cycle. Alcohol had no effect on resting ventilation or the ventilatory response to CO2 during either phase of the menstrual cycle. However, alcohol significantly decreased peak integrated genioglossal EMG activity during the follicular (low progesterone) phase but not during the luteal (high progesterone) phase of the cycle. The relative alcohol resistance of genioglossal EMG activity during the luteal phase may explain in part the low incidence of sleep-disordered breathing in premenopausal women and the benefit that some male patients with obstructive sleep apnea have derived from treatment with progesterone.