For some people like Mike, sleeping mask does help to put one to sleep easier; but for me, it is not about the lighting.
When I was young, I could easily doze off with the white light on and right above me. That was when I was carefree and there were not many things to be troubled about.
I suppose the main problem with able to sleep instantly is that my mind is too active no matter how tired my eyes are. Very often, or almost every day, once I close my eyes thoughts would fill my entire head; I have to struggle so hard to open my eyes to realise that everything turns blank immediately but the mindful of stuffs restore immediately upon shutting my eyelids.
Wasting more than three hours on the bed daily before dozing off is killing my time.