I acknowledge that the following is anecdotal, but I thought I would share my experience.
First day - took magnesium glycinate (100mg) at dinner and had best night of sleep in years - deep restful sleep, not surface sleep.
Second day - took magnesium (100mg) with zinc (22mg) at dinner (read somewhere they work together) and sleep was not good.
Third day - took magnesium (100mg) and zinc (22mg) at lunch and then took magnesium (100mg) by itself at bedtime. Had another outstanding night of sleep.
Not sure if it was the increased total daily dosage of magnesium that worked or separating the zinc from the magnesium, but I will continue to take as I did on day three. Sure beats lorazepam or benadryl and the effects of taking those.
I’d like to offer my 2 cents worth of advice: For at least 15 minutes before getting into bed, in a dimly lit room with no distractions, do slow deep breathing, through your nose if possible, with attention only on your breath, the rhythmical movements of your lower abdomen, middle and upper rib cage as they expand and contract - sort of like in mindful meditation. For a more detailed and methodical approach to this kind of meditation, I recommend some reading (or lessons) about the ancient practice of QiGong (aka ChiGong).
There are lots of things out there but a simple one if you have trouble falling asleep is to use blue-blocking glasses 30-60mins before your intended bedtime. The most effective blue-blocking glasses are, in order: red lens, then orange coloured lens, then yellow lens. You can buy these quite cheaply online, e.g. eBay ($10-20 usd). I sometimes give them away free to my patients. It’s based on science to do with blue light blocking melatonin production.
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