Thank you for clarifying.
Your son may have a higher EQ that is affecting how her reacts to other's feedback.
Because of your experiences from childhood, you actually are aware of what he's going through and you're sympathetic and trying to help him.
The approach you may try with him is to let him know that you have been in his shoes (you do not have to go into details with him) let him know what had helped you, how you managed, and remind him that you're there for him even if he does not want to talk about it at this time.
It would help to focus on his strengths (whatever they are- you know him best) and foster these in him by continuous encouragement and praise for work well done. Even complimenting the desirable traits in his personality are empowering.
There may be some activities that you can slowly introduce to him such as- walk in the back yard with you with a flash light and talking about how his day had been at school, then the following week going out to gaze at the starts, perhaps when it is warm ask him if he would like to have a sleep over (either invite a friend of go to someone's house) At all times you remind him that darkness is part of life just like light is (the two have to exist) You can let him know that night time is a time for animals, plants and people to recharge their batteries, growth occurs when rest is present, etc.
Look into using some on line educational videos to show him that some creatures are more active at night ex: bats, owls, cats) Try to find out what about darkness is comfortable to him- is it because his imagination is wide fearing something will happen, is it because he's genuinely anxious but no identifiable reason can be pin pointed, is it because it reminds him of an incident where something sad or scary had taken place in the dark, etc.
Indigo Dreams: Relaxation and Stress Management Bedtime Stories for Children, Improve Sleep, Manage Stress and Anxiety (Indigo Dreams) by Lori Lite (Audio CD -