Hello ! I read your question and understand your concern. The sleepy feeling during day may a concerning sign of cardiac disease. It is a common sign in chronic cardiac failure and it is an important risc factor in cardio vascular disease in elderly persons. It may be caused from the low brain per fusion, because of carotid artery narrowing ( from atherosclerosis which is also complicated with coronary disease). I would like to know if you sleep well, if you snore during sleeping. Sleep apnea could cause sleepiness during day . But you say that your sleep is deep , so a sleep apnea is less probable. I would recommend a good follow up from your cardiologist, a heart evaluation with echography and ECG. In some clinical studies in cardiac patients treatment with warfarine has shown to reduce daily sleepiness. Hope to have been helpful. Thank you for using HCM! Best wishes, Dr. Abaz