Night time versus daytime transient ischaemic attack and ischaemic stroke: a prospective study of 110 patients

Ischaemic stroke occurs only in 20%-40% of patients at night. The aim of the study was to compare sleep and stroke characteristics of patients with and without night time onset of acute ischaemic cerebrovascular events.

A consecutive series of 110 patients with transient ischaemic attack (n=45) or acute ischaemic stroke (n=65) was studied prospectively by means of a standard protocol which included assessment of time of onset of symptoms, sleep, and stroke characteristics. An overnight polysomnography was performed after the onset of transient ischaemic attack/stroke in 71 patients. Stroke and sleep characteristics of patients with and without cerebrovascular events occurring at night (between midnight and 0600) were compared.

A night time onset of transient ischaemic attack or stroke was reported by 23 (21%) of 110 patients. Patients with daytime and night time events were similar in demographics; risk factors; associated vascular diseases; clinical and polysomnographic sleep characteristics (including severity of sleep apnoea); and stroke severity, aetiology, and outcome. Only the diastolic blood pressure at admission was significantly lower in patients with night time events (74 v 82 mm Hg, p=0.01).

Patients with night time and daytime transient ischaemic attack/stroke are similar in sleep and stroke characteristics. Diastolic hypotension may predispose to night time cerebrovascular events. Factors not assessed in this study probably account for the circadian variation in the frequency of transient ischaemic attack and acute ischaemic stroke.