I feel like I'm constantly losing touch with my humanity, I'm a lot meaner or sullen

Starting this off with, yes, I have seasonal affective disorder. But that doesn't explain why I seem to be lacking in the warmth and empathy I usually have when it's sunnier.

I'm a lot more impatient, I'm guarded, way less tolerant. I can't say it isn't me, because it is, but that's not who I believe I am in my heart of hearts.