I grew up with something called exploding head syndrome. It means sometimes as you fall asleep or wake up you can hear loud noises. I was really sure a bomb had gone off but everything was normal which scared and confused me and no one else had woken up.

Something that is important with this is not to be sleep deprived, that really makes it worse, or did for me. Also I benefited some from taking some quiet time before sleep, for me it happened more if I went from activity straight to going to bed and sleep.

It didn't fully go away until I was around 30 though.