Circadian rhythm in acute stroke.

Ischemic events have been reported to follow a circadian rhythm. The frequency of myocardial infarction is found to be increased between 6:01 a.m. and 2:00 p.m. Blood pressure also demonstrates a similar circadian variation. Circadian variation of stroke onset has also been reported, but with contradictory findings. To determine this in the Indian population, we studied 182 consecutive patients of acute stroke admitted to our words within twelve hours of onset. The frequency of onset of stroke was found to be highest between 6:01 am and 2:00 pm, in patients of infarct as well as haemorrhage. Patients of hypertension also showed a similar variation. Thus, the identification of periods of high risk, may help by matching drug doses with periods of vulnerability.