Most people benefit from 400 to 1,000 mg a day, and it is best to take it in divided doses. Dr. Hyman recommends 200 to 400 mg of magnesium citrate or glycinate before bed to relax the nervous system and muscles to improve sleep.’ve been tracking how much insulin I use, and for years my average amount of insulin used was 5.5 vials (5500 units) per month. I read that magnesium helps with insulin sensitivity, so I started taking 500 mg of magnesium oxide a day (250 in morning, and 250 before bed). Immediately I saw a difference.