Postcreative depression

I have been so excited programming at work that I got up and went to work early. Now if you know me I wake up early anyway so I got up even earlier - now that's saying something. Well I got to work and started right in programming. I was focused. At about 1:30 PM having taken 22 1/2 hours over the past four days it was done. It was working. It was organized. It was slick. I was feeling the internal joy of attacking this challenge, surmounting the obstacle, and achieving this self-set goal. I posted the results in our code repository. Afterwards I felt relieved but somewhat sad. I no longer had that tingle. My next job was to do system design documentation and had nothing to do with this programming. I consider it more drudge and less creative. The adrenaline was gone. So by 5 PM I was totally exhausted. My brain didn't want to work anymore. I walked slowly down the walk to my car and went home. I was feeling postcreative depression.