The learning curve -the more I study the worse I play

Why sometimes happens that the more you study the chess the worse your play?

Well one of the reason is the learning curve:

The reason you seem(!) to play worse may be learning curve and the way human nervous system is built

 Human learning curve has plateaus and declines and it takes time for new learnings to be integrated. There is a work in progress in your nervous system and resources are busy building new neural pathways that may be reason your current play seems to suffer.

And emphasis is on it seems, cause you playing worse may very well be your subjective appraisal of your game or just a  natural short-term fluctuation in your rating if you base your judgement on rating.

Keep in touch cause more of my writing on this interesting topic is to come here soon.