I'm not sure where I heard that magnesium is supposed to help prevent nightmares and also help you sleep better at night, but I started taking this last night, and it seems to help. I visited my doctor this morning and asked him about it, and he said that it is fine for me to take this supplement. It might also help with my hypertension, but that will be difficult to tell.
This is the one I am taking. The bottle says that three pills is the correct dosage, but I took only one. I might increase my dosage if I do not get the results I want, but so far, it seems that one pill did help, and I did not have nightmares, although I only slept for five hours without waking up. Recently, I've only been sleeping for three hours before waking up during a nightmare, and then I stay awake for about two to three hours before being able to go back to sleep.