I use magnesium frequently - sometimes in the day for anxiety and most nights for sleep. I find it very helpful. My husband has also started using it to lower his blood pressure and control anxiety. Max daily dose is 400 mg. Dollar General has a formula that also has calcium and zinc in it and the magnesium dose is lower than 400mg (I think around 120mg/tab) so you can take it up to three times a day. My husband says this one works better than the straight magnesium for him.