It's normal to miss them and go through some depression. Keep in mind that you are depressed and don't do anything stupid on the spur of the moment...
I have my own sleep issues, I wake up every 1 1/2 - 3 hours typically...
The friends are most likely keeping to their own lives and do now know what to say or do to help you out... It may be sorta awkward to them and they do not know what to do or say...
I've dealt with some depression also, it will not go away if you don't want it to... You have to decide to move on and try to get a better outlook to help get you out of the depression when the time comes... Hang in there Tom, it takes time....
We're here if you need to talk...