Hi. Thanks for your query. Noted the history of waking up at 5 am to do habitual bowel movements, feels hot and begins sweating within 10 - 15 minutes, followed by chills within a few minutes, dizziness, have to lie down on floor for a few minutes because of weakness, recover in a while as if nothing has happened... As per the history you have provided, the most probable causes are: - Syncope attack due to imbalance between the sympathetic and para-sympathetic nervous system. - Hypo-tension attack. - Vascular problems of the intestines can cause the similar problems. - IBS that is irritation bowel syndrome. I would advise you the following in such a situation: Get a clinical evaluation, examination and investigations as mentioned below: Contrast enhanced CT scan of the abdomen with study of the vascular components too. Tests of the blood, stool and urine. Colonoscopy as this is related to the passage of bowel movements. Any other investigations as may be decided after clinical evaluation and preliminary reports. This will get the proper diagnosis which is very important to have proper treatment.