At night, I sometimes can imagine things, but only bad things, like nightmares, and the images are actually projected onto my surroundings, like I can see them with my eyes open, and the only thing that stops them is looking into a light, or turning the light on. It isn’t SP, because I can move, although I usually end up sobbing in a heap, wishing these things would go away. Most commonly I see spiders, snakes and monsters. What is this?!
how much time does it take for the cratures you imagine to get projected into the room?
Fear is a human emotion and “alarm system”. Dark is something unknown because we can only see objects in light. Being in danger and not know what might come over us makes us trigger an autonomous emotion, destined to help protect ourselves - fear. Sometimes it “exaggerates” - like your case. The fact that you are in the dark triggers fear because you don’t know what it is - the dark - and so you brain is running out of control making you see things.
I have also experienced deep fear and I can tell it is the most frightening feeling ever (wouldn’t you guess that ?? 
). What can you do ? The answer is that you can’t do much. But what I did, which proved to have good effects, was:
1. Turning the lights on (yes !!)
2. Try to get your mind over the fact that you are in unknown (i.e. watch a romantic movie, play a video game, take a walk etc.)
3. If you can talk to someone do it ! (this proves the best results)
4. Have someone stay near you (this proves also the best results)
5. If alone, the best thing you can do (and you will do it in that fear desperation) is… praying.
Extremely hopeless situation, but try rolling over with the face to the wall, cover yourself in your blanket and start daydreaming. Eventually you will flow away with the daydream and fall asleep.
I truly hope you will get over this 
Thank you! I’ll try those things if it happens again. Trouble is, the creatures are there when I close my eyes and open them too. They aren’t so common. I guess I make myself too tired to stay awake over them. But thanks again, I really appreciate it!
And Zenahr, a few seconds at most.
It’s a free scary movie in your head. Only better. It’s a little bit of excitement. It’s a fascinating opportunity to learn about yourself. It’s possibly a manifestation of the collective unconscious. It’s more interesting than seeing nothing.
It is all these things and more. You can pick and choose.