@ Rick: Magnesium can be sedating (or relaxing) to some people. It also dilates blood vessels, more so for those contracted to some extent to begin with.

I always put my mag lotion on at night. And that is when I used to take my SlowMag also.

You might lower your dose, or split it up during the day (which more approximates how magnesium is derived from food eaten). Or you might want to try the new topical form...Morton's. Enough does get into the blood stream if you apply it correctly. I rub mine into my wrists and inner arms where the veins show...for systemic absorption. It has been very helpful for me this way.

If I remember correctly you are using that ACE inhibitor still? That can be additive...since yours is one that enters the brain.
Since you use an ACE inhibitor, also, you may have some lowering of blood pressure as well. Can you take your pressures daily... before and after using magnesium? That may reveal something.

Once I quit the evil lisinopril, my mind cleared up considerably and I had much more energy. Not to mention I got my life back too.