in high doses can give a "hangover" I have found. When I worked some midnight shifts several years ago, I needed 6mg to fall asleep in the morning (10-11am).

I used it thru my menopause, on and off, successfully. I found that it shortens the sleeping time for me, but that time was restorative. In other words I did not get a full 7-8hrs on it, but more like 4-5.

What really worked long term for me was B12 supplements. Even tho I tested in the 800+ range I took some during my menopause and found that over time it enabled me to sleep more naturally. 1mg methylcobalamin is what I used taken at night on an empty stomach.

One thing that also works is to NOT get up if you are insomniac. Exposing your eyes to light, affects the melatonin receptors in the retina, turning off internal melatonin production. This in turn makes the insomnia a vicious circle.

Recently with age, I found my melatonin cycles totally screwed up...to the opposite point. I have had to resort to light therapy to get back on track.
Oversleeping and depression was the result.
This may be a combo of aging and working swing shifts too much.