I have an inkling that it might be, but when I've tried to describe how I feel, people give me funny looks.

Like, when I'm depressed, I don't necessarily feel sad. I feel exhausted. Physically it feels like my brain has the flu- with my head all achey and my brain all slow. 

People say those with depression need to stop living in the past, but often, I don't feel like I'm THINKING any particular thing. I don't think I'm bringing this on myself. It just...happens. 

I don't know though. Maybe people with other types of depression feel similarly. Or maybe another way entirely.