ObjectivesObstructive apnoeas during sleep are associated with marked cyclical blood pressure fluctuations in men with obstructive sleep apnoea (OSA). Haemodynamic responses to OSA in women are largely unknown. We aimed to investigate haemodynamics during apnoeic events in women with OSA and to assess the influence of the menstrual cycle on these responses.Design and methodsFull overnight polysomnography and continuous non-invasive blood pressure monitoring was performed in 13 women with OSA during follicular and luteal phases of the menstrual cycle. Change in blood pressure (ΔBP) from pre- to post-apnoea termination was measured for each apnoeic cycle.ResultsOnly 10 of 13 subjects ovulated. In women who ovulated, pressor responses to apnoea termination occurred in both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, but substantially increased during the luteal phase of ovulatory cycles [NREM change in mean arterial pressure (ΔMAP) 12 ± 3 mmHg during the follicular phase and 20 ± 3 mmHg during the luteal phase,P< 0.001; REM ΔMAP 11 ± 3 mmHg during the follicular phase and 23 ± 3 mmHg during the luteal phase,P< 0.001]. Sleep apnoea severity did not change during the cycle in NREM sleep, but was reduced in REM during the luteal phase. Changes in pressor responses were absent in nonovulating subjects.ConclusionsObstructive apnoeas in women were associated with marked blood pressure changes, similar to those previously reported in men. While respiratory events improved slightly in the luteal phase, blood pressure responses to these events increased by approximately 100%. Thus, the menstrual cycle has discordant effects on the respiratory and cardiovascular effects of OSA in women.