Dear doc, my father 62 year old, Driver by profession has been experiencing sudden blackouts in the evening or ant night, while in the sitting posture, which lasts for about 1 minute. I am worried as cud this be am immenent CVA or TIA can u please suggest me some differential diagnosis for the said condition. He has a past history of hypertension and was a chronic smoker but not now. No history of diabetes but has allergies to dyes. Kindly help