How to have a child gain confidence for bedtime?

I have a ten year old child who is very anxious and afraid at bedtime. Either he doesn't know why, or there are monsters. We've been through making his bed as cozy as he likes or changing the room layout. He has stuffed animals he loves.

Now thanks to AI, I'm going into his room every 5 minutes just so he hears me enter without saying anything. That seemed to help but even with that he would call me in between because he's afraid, wants to drink or another question. We already go over the list of drinking etc beforehand. I read him a story every night, unless it's incredibly late.

How can I get him to relax and gain confidence with this, any experience?

Updates
4 mo
I just thought about simple breathing exercices before bedtime, the ones that turn off fight or flight. I'll go with that and see if it helps him. Thanks all.
How to have a child gain confidence for bedtime?
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