To me, a jigsaw puzzle is not 'mild stimulation.' Most of the effort is visual. That is a lot of effort.

One may need an occasional nap during the day. One of the problems with too much bed rest is the restless tossing and turning and bad posture. If one can truly sleep then wake up refreshed, the sleep should be worthwhile. But, the gentle stimulation is needed to encourage good brain blood flow. If the sleep is full of stressful dreams, that can be a problem.