Hi,
I got a young male Syrian (about 8 or 10 weeks old when I got him from the pet store) about a month ago. He is quite shy and doesn't like interaction very much. He doesn't mind being touched or stroked. He is very tame and doesn't mind me playing with him or letting him out the cage, but he will start to get stressed and frenzied movement if I play with him for more than 20 minutes. He is also quite sensitive to stress and I accidentally wake him up sometimes if I'm being noisy.
Back in February and in early March he was doing very well up until the past week or two. He used to go on his wheel almost all hours of the night and he would wake sort of around 9-10PM. Nowadays, he sleeps pretty much all day and most of the night, and doesn't wake up until 6 or 7 AM. He is eating his food and drinking water, uses his toilet often and still likes to play and such. He also uses the toys and wooden chews I have provided him.
I give him occasional treats (carrots, brocolli, etc.) but sometimes I believe I give him too much of these foods. I have reduced the amount of treats I give him to and he has approximately 1 and a half tablespoons from his food packet every day. I still supplement his diet with fibre-rich foods like apples or grapes, which I think also contain a lot of sugar.
I am getting very concerned about my ham ham as he has barely used his wheel this week and this suggests to me that he may be getting lethargic or depressed?

. I have heard him using it in the mornings but since I am half-awake at the time I can't always confirm. I have done my very best to ensure my little friend gets the best life I can give him but it's making me extremely anxious. Could his diet be to blame? Any help would be greatly appreciated.