If Daniel has nyctophobia,,,

[Soto]

Just wanted to note that Daniel had nyctophobia all the way back when he was a small child. It can be read in the loading screens; his father urges him to go into the basement, he accidentally breaks a jar of paint and he cries and knows he will be punished.

The loading screen actually read:
"[Daniel] wasn't particularly afraid of the dark, but he had always disliked going into the basement."

So he possibly didn't have the phobia by this point, and the event in the tomb spurred it on or one of the other theories that you guys came up with.

I didn't quote it, I just summarised it. But no, he didn't fear the dark, he feared never being able to escape it:
- "He wasn't particularly afraid of the dark, but he had always disliked going into the basement. His father urged him on to fetch the red dye. As he stepped into the dark, he thought, "I will never escape this""
- "He cried like the little boy he was. All alone in the dark basement, broken glass tearing at the flesh of his naked feet, and blood mixed with blue tint."

He didn't like the dark back then. He always had a fear of being trapped in the darkness forever, and I guess you could say that the incident in the tomb triggered it. My point is just that he developed the fear earlier. I agree that the incident must have been very traumatising to him, especially if he never really liked the dark.