My daughter had vivid dreams when starting an AD. She had some while on it and now that she is tapering off (Lexapro) she is having very vivid dreams again. So much so that she has mentioned not always being able to tell if it's real or a dream. Her concentration and memory are not what they used to be but have seemed to be somewhat improved now that she's on a lower dose of AD. Don't know if that will continue to improve as she lowers the dose or not. She's in college too and all this isn't helping.
Anyway....just thought I'd mention it in case your son was also reacting to his medication.
The reseting of his clock has been interesting. He has to keep a sleep journal of what time he goes to bed, how long it takes him to fall asleep, how many times he wakes up, etc. The crazy part is that they reset the clock through sleep deprivation. For the first three weeks he had to wait until 2:30 a.m. to go to sleep and get up every morning at 7 a.m. Then it was 2:00, 1:30, 1:00, The important part is getting up every morning at 7 a.m. He now is allowed to go to sleep at 12:00. You can imagine how difficult it must be to complete a college semester on this sleep schedule. He has been tested at the sleep center twice and they say that his sleep is improving; however, he is still suffering from "zoning out" or daydreaming. He has a difficult time staying in a conversation and maintaining any extended time of concentration.
I'm inclined to agree with you. I think it's more likely a sleep disorder rather than depression. If he's not going through his REM cycle that could really mess him up. He's not properly rested. What do you mean about reseting his clock? How is he doing that? Another option to think about is to have his sleep monitered for apnea. Does he snore, do you know? I'd check into that. Another thought is if he has ADD. I was never officially diagnosed because I didn't have the hyperactive part of it but I struggled in school because I always daydreamed and had a hard time concentrating. Just a thought.
It could be that the stress of school is just making it difficult for him to fall and stay asleep. You've probably noticed when you're stressed or worried about something how it will be hard to fall asleep and sometimes you wake up in the middle of the night thinking about and rehashing things. Fortunately, we're coming up to Summer and hopefully he'll be able to take a break from school for awhile.
I'm not sure I was much help here. I hope you can find out soon how to help him get the rest he needs. That's so important. Best wishes.