Hi Mew151 !
First of all, sorry for the long post 
Well, I experienced many such things. During the day even if you see the scariest movie you won’t get scared. I bet on that. Now, when night comes suddenly you start thinking about the scary things that you read/watched that day.
It’s like that, day (the sun) has something special. We can’t know that an it’s possible to never know why. During the day your “guard-angel” (that is your interior mind and soul) is strong an brave, ready to face anything that may happen to him. Now the night has strange elements too which is the opposite of the day - you are weak, every shadow scares you and you think of yourself “Hey ! What’s going on with me ?!”. That’s one of the many mysteries this world has.
How to get rid of that ? Well, as I said before, everyone has a guard-angel. I prefer calling it that way because it makes more sense. In fact this guard-angel is your deep emotional state, your conscious and your spiritual life. So, during the day that angel receives power from the light the sun offers us. During the night strange thoughts wander our mind, and they appear like from nowhere.
During the night our guard-angel is very vulnerable to every thought. It needs power and strength. Take a walk outside, somewhere where people are. If the guard-angels of 2 or more people meet, they receive power and you won’t get scared anymore. You can feel that just being with another grown-up person. You could also simply pray to God to give you enough strength to carry on. But, let the guard-angel speak for you in your pray. Just say whatever comes on your lips.
Don’t believe me ? Don’t think such day and night elements exist ? If you don’t believe me, take this test. Just click the spoiler:
[spoiler] Well, let’s do a test shall we ? During a sunny day, go outside look at the clouds and at the bird (if any). Look at the trees look at the light the sun offers us. Then, while looking thing of things like demons and Satan. Try to scare yourself. You will notice, that even your darkest thoughts won’t have any effect and you’ll continue to feel happy.
Now at night, turn the lights on. Take a chair in front of a large window and look outside, look at the stars and at the black sky. Look at the darkened world. IF you can, close the lights. Open your window (if it’s a warm summer night). While looking at the things night has to offer (stars, moon etc.)let the same dark thoughts you had in the day wander your head. Think about something scary. You’ll immediately get freaked out and shake in fear looking around your room while biting your nails in fear.
If you take this test and don’t feel exactly what I said (age doesn’t matter), it means you either believe that God truly exist and he will help you and helps you, and thus you won’t get scared (very true), or you are not telling the truth or it’s not night. Take the test…if you can 
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I’m telling this from 100% personal experiences. I felt this. I know this is true. The best thing to do if this happens again is to interact with another person.
Even tough this happened to you, it may not happen to everyone. People who never saw a horror movie or read a scary book have bigger chances to not get such fears. Most of the people don’t have them, but there are lots of people who have them too. Autosuggestion could help too, but only if you truly believe in yourself.
Hope that won’t happen again for you !
Good thing I didn’t hallucinations!
(lame pun, i know!)
I’m sorry that you had a bad night, Mew.
I usually read a book until I can’t stay awake any longer.
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Let fears fly away 