On the job front

I haven't been feeling great about my job, as I mentioned. In fact, I haven't felt very good about it since I returned from my leave of absence. Though I do feel a bit better today about my options. My firm lets people cut hours (which I sorta forgot about until someone reminded me), so, for example, I can go down to 1600 billable hours a year for 80% of my pay. 1600 hours is sounding really good right now. I am thinking seriously of doing this. I never really thought I would, but I am. I am a little worried that the partners that I work for aren't going to like it, but I feel like it is necessary for my mental health. I am sure someone has to approve it. I am sure I need their blessing to do it, so I'm not sure what to do really. I just feel like I want to do it. Even though yeah, things are better than they were, I feel like I am barely hanging on some days and for some reason all this extra responsibility is being heaped on me at work. I don't mind some extra responsibility but this is getting to be too much at once. I feel like for health reasons I need to cut my hours down and lower my stress level. Is that unreasonable?