@Wetrix @TheDoctor
> Sleep issues. It’s pretty common to hear a sound just as you fall asleep or wake up. And it’s usually not something to see your doctor about. But if you fall asleep randomly (narcolepsy) or have a hard time falling asleep (insomnia), it’s much more likely to happen.

I've seen an opinion on some other website that a good 7-8h sleep and a stable sleep schedule would help.
Some other website says hearing things when you fall asleep may be caused by stress.