Wake-up stroke is defined as ischaemic stroke with unknown time of symptom onset, when patients go to sleep normal and awaken with neurological symptoms. This type of stoke accounts for about 20% (14–24%) of all ischaemic strokes. The high incidence of wake-up stroke may be associated with diurnal variability of heart rate and blood pressure, coagulation processes, as well as episodes of atrial fibrillation, which are more common in the morning. The risk of wake-up stroke increases during REM sleep. Individuals with obstructive sleep apnoea account for the majority of patients with wake-up stroke. Until recently, wake-up stroke was considered a contraindication for reperfusion treatment due to the unknown time of onset and a potential risk of intracranial bleeding. The latest research has shown that wake-up stroke occurs shortly before awakening. Therefore, these patients could be qualified for reperfusion treatment, which would improve their clinical status.