I'm not the person you asked, but the most important part isn't the dosage, it's the form.

Basically, make sure the magnesium tablet is anything but magnesium oxide - our digestive systems cannot absorb that. Just about any other form (there's like... six of them) will work. Magnesium oxide only helps with constipation, which is also important I guess but a completely different problem.

I take Magnesium Glycinate 400mg once a day. I feel super relaxed after taking it, although I have noticed an uptick in muscle twitches, which extra calcium seems to mitigate.