The study only pertains to the first week to ten days. It does not apply to later recovery periods.

I wonder if your feeling you need a nap or rest is a response to over-stimulation or otherwise overdoing it. Short periods of cognitive rest can be helpful. Simply closing your eyes for a few minutes and listening to no stressful music or other audio stimulation can be a big help. It does not mean you need to sleep. You mind may just need a short break.

Sometimes, just a change of task or environment can do the trick.