Circadian fluctuations in timing of onset of acute ischaemic stroke

Fifty patients of acute ischemic stroke were analysed to find out the time of onset of stroke. The number of strokes per 4-hour period were the following: 12 midnight a.m., 4 [8%]; 4 a.m. -8 a.m. 15 [30%]; 8 a.m. -12 noon, 12[24%]; 12 noon - 4p.m., 6[12%]; 4 p.m.-8 p.m. 6[12%] and 8 p.m. - 12 mid night 7[14%]. It was observed that most of the strokes occurred between 4 a.m. and noon [54%] and the most frequent time of stroke onset was 4 a.m. -8 a.m. It was also noted that 44% of the strokes occurred within first hour of awakening. This study has indicated that there is a circadian variation in the time of onset of ischemic stroke peaking in the early morning and deceasing as the day passes