[Breathing disorders during sleep and the circadian rhythm of strokes]

Similar to myocardium infarct and sudden death, stroke presents a circadian rhythm with a maximum incidence of the beginning of the symptoms during the first morning hours. It is believed that this morning pick is secondary to haemodynamic, haemostatic and autonomic changes that happen during sleep, the sleep-awake transition and after wake up. About 25% of stroke, especially lacunar and atherothrombotic infarcts, occurs during night sleep. Usually, the symptoms are perceived for first time when the individual wakes up in the morning although stroke could have occurred long time before. These individuals are excluded from thrombolytic treatments and therapeutic trials. The patients that develop an ischemic stroke when sleeping presents more obstructive apneas during the acute phase of stroke than patients that suffer stroke during wakefulness. It is known that apneas are associated to oxyhemoglobin desaturations and to important haemodinamic changes and their treatment reduce cerebrovascular morbidity. These findings suggest that apneas, likely associated with other risk factors, can worsen or precipitate an ischemic stroke.