We too are struggling with nighttime fears. I have a 12 year old daughter who is scared to death to be alone at bedtime.
Passing along a few things that have helped or I have learned:
First of all during a comfortable, safe quiet moment ask them about it. I received so much insight by just asking. Next I asked her what makes her feel better (she said the blinds down, door shut, music on...) Up till this point I was lifting her blinds everyday, keeping her door open and going round and round with her about music on while trying to sleep. We compromised on soft, quiet music while falling asleep. She said it helps her not hear every noise.
I brought this up this morning with 4 tweens at carpool, wow was it insightful. They all verbalized their fears and the "rituals" and comfort strategies they do: fan on, music, moved the bed away from the door and window, phone in the room.
The one common comforting item was a pet sleeping with them. My daughter is obsessive about finding the cat before bed and now I know why. The other girls today were also stating that "anything living and breathing" in bed helps-mom, dad, animal, even sibling.
I do think the fears have been much worse as of late (Halloween time with scary masks, movies, stores everywhere).
So what I am finding out is that this is a real and common fear among children and there are many small things that make a big difference especially just listening to their concerns.
Wishing you and all your family sweet dreams.
Oh, also, I played soft music to fall asleep. It helped take away the creaks and other night noises.
I was like that when I was a kid, I watched too many scary movies. He may have even convinced himself there is a being in the house! Be sensitive, try to calm his fears, and even though halloween is coming up, really try to cut out scary shows. Hope he feels better.
Have you tried staying in his room with him until he falls asleep. It's just a thought. Good Luck