To study the  pattern of circadian rhythm of stroke in Sudanese cohort  and  its associated  risk factors  particularly  stroke type, posture ,activity  and arterial territory .

Circadian rhythm have been recognized since 1970 with the majority of publications suggesting early morning peak. Many hypothesis and suggestion aimed to explain the occurrence of this rhythmic phenomena incriminating exogenous factors such seasonal variation , diet, exercise ,sleep/wake cycles. . Endogenous physiologic factors like hypertension, autonomic nervous system, coagulation temporal variance. No conclusive evidence is currently available to explain this phenomena.

This is a facility-based study that included a cohort of 162 patients presented with acute stroke to specialized hospital in Khartoum. All patient underwent all necessary investigations to determine the cause and type of stroke, territory along with time and posture. Descriptive and inferential statistics were performed to analyze circadian rhythm pattern.

57% of the study population were males with age ranging  19 - 95. Ischemic stroke was more frequent  (83.3%) and (63 %) suffered from stroke of the anterior circulation.Hypertension, combined hypertension and diabetes and cardiac  constitute common risk factors. Two peaks of stroke were observed, one in the early morning and a second smaller peak in the afternoon end late evening .85% of the study population were at rest  (63.1% ) .

 Age and sex have no significant effect (p=0.326 , p=0.607 respectively ) . No association between the type or territory of stroke and the circadian rhythm (p=0.356 ,p=0.101 respectively) . No association between the common risk factors and the circadian rhythm  (p=0.275). Significant  association between the circadian rhythm and posture of the patient  was noted (.003).