Hydrochlorthiazide is a diuretic, it means it flushes extra salt and water on urine and brings blood pressure down, so it should be taken in morning or at most on afternoon, night dose NOT recommended as it would result in you going to pee throughout the night. You are true that max heart attacks and stroke occur in morning, however the long term effect of hydrochlorthiazide is it relaxes the walls of arteries, and hence it has long lasting action which would cover the night even when taken in morning, even though it stays in the blood between 6 to 15 hours. Lastly it is not a powerful anti hypertensive and would be started alone because your blood pressure would be just borderline high. Chlorthalidone is a more longer acting diuretic as compared to hydrochlorthiazide if you need to switch. Regards Dr Priyank Mody