It doesn’t sound like other variables were eliminated in this study. For example, what if everybody who is able to take a nap held and office job and is now ret

It doesn’t sound like other variables were eliminated in this study. For example, what if everybody who is able to take a nap held and office job and is now retired while those who don’t nap still have to work? Sometimes I will go nap with a problem in my head and will wake up with the solution. I believe it helps, but I still don’t know if it is a placebo effect.