The problem with depression, as I'm sure you well know, is that it's extremely debilitating. It also takes a huge toll on the emotions, making you question how you really feel. I can easily understand how someone, especially someone that tends to keep things to himself, wouldn't want to share how depressed he's really feeling. Not to mention, we're still battling stigmas surrounding mental illness, medications, and therapy.

I'm a little curious about your ages, and whether or not either of you work. It just surprised me to see how much time he spends sleeping and alone holed up in his room. If you two are at an age where modern society expects him to have a job (ie, not retired, etc.), perhaps that's another problem he's dealing with -- not feeling like he can provide for you. I know it's the 21st century, but from where I'm sitting, a lot of guys still have this ideal in mind where they take care of their families/women financially.

Also, it seems like he's at his best in the morning. My fiance is the same way. He feels like he can be productive in the morning, but the later on in the day it gets, the more depressed he gets, and the less he accomplishes. But with this is mind, perhaps you could encourage him to take walks with you, maybe before his shower, or right after. When it gets cold, you could go to a mall and walk around or you could get a gym membership at a gym that has an indoor track.

Good luck! Sending warm thoughts your way