Some of the time doing something, anything, is better than doing nothing. Of course this doesn't work long term, or even mid term, that's probably why 2 of more dozing sessions a day.
It may simply be distraction, it takes a while for the body to figure out nothing has changed, especially when constant internal monitoring alters perception, and by the time that approaches, time for more placebo capsules.
Of more interest, to me anyway, is why people on stronger pain relief noticed the placebos didn't do squat, and then a few days later, fully armed with this knowledge, some reported they started working.