Respiratory disorders are known to disturb sleep patterns. For example, recurrent apneas and hypopnea lead to intermittent hypoxia that provokes arousals and fragmentation of sleep, which in turn may lead to restless sleep, and excessive daytime sleepiness. Repetitive apnoeas and intermittent hypoxia may also elicit sympathetic nervous system activation, oxidative stress and elaboration of inflammatory mediators which may cause repetitive surges in blood pressure at night and increase the risk of developing daytime hypertension, atherosclerosis, heart failure, and stroke independently from other risks. There remains a need for improved methods for monitoring, identifying and/or determining breathing cycles, in order to obviate these risks.