I was the same due to severe nightmares i had when i was young, start by living the light on when you sleep (maybe dim it) so there is just enough light so yu can see. And just force it into your brain that nothing can happen to you, the fear mostly comes from the frequency that your brain/consciousness is operating in at that stage which causes you to feel nervous/anxious/fear only because your unfamiliar bieng awake while operating at that frequency. Fear comes from uncurtainty. So keep pracctcing and see how long you can last and every time you gain more confidence and go little bit further. You will eventually realise even if you see scary things it woint matter because it cant do anything to you, but if you do for e.g (scary charector/demon like creature shows up) just show geniuene love to it as if its your mum and it will no longer be scary and either dissapear or become friends with you, its the same in the dreams, i learnt this awhile ago. Anyhing scary is a manifestation of your fears etc so if you loose the feear in you and replace it with love what you see changes.