When muscles contract involuntary, we call it a cramp. Given that cramps are usually caused by fatigue or strain, the involuntary reaction succeeds a, hopefully, voluntary action. A soccer player with cramps towards the end of a match isn’t unusual. Action, reaction.
What about the brain, though? If muscles cramp after submitting them to continued strain, maybe the brain could too?
All work and no play makes Jack a dull boy. Those who demand lots of intensive intellectual capacity from their brains need decompression time to relax the particular muscles or brain.
After all, cramps cramp growth.