<s>[INST] In the past year, I ve had two episodes of fainting (syncope?). Each took place after suddenly rising from sleep at night to respond to my husband in a hospital bed at home (has a brain-related diagnosis). Never fainted before, but the first time I took about 3-4 steps before fainting , landing on the floor and my head hitting the floor. The 2nd time i actually was almost outside of our bedroom before fainting, again landing on the floor and my head hitting the floor. Could this be from dehydration or low blood sugar. I am petite, weigh 85 lbs., and probably don t drink enough water. [/INST] Hello, There are a number of reasons a person can faint who has never had this problem before.  You've identified 2 very common reasons why people faint or nearly faint. One is dehydration and hypoglycemia (low sugar).  You really need to drink a lot of water daily (good fresh unadulterated water is the best fluid to feed your body). Also, make sure you eat 3 really good meals daily and have a couple of snacks go ahead dare to weight 90 lbs.! Don't skip meals. Also, check your medications especially if you're given anything to control blood pressure, cholesterol, or diabetes because all of those types of medications can lower blood pressure. It is possible that you may take too high a dose or there could drug to drug interactions causing this problem.  Drink, Drink, Drink! And at night, make sure before you start walking out of bed. Sit to the side of the bed, dangle the legs, move them about, count to 30 THEN, get up and start walking. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Dariush Saghafi, Neurologist </s>