Yesterday I slept all day and now feel much better today because of it. The days I just do quiet rest as in stay active around the house, do jigsaw puzzle, and such, I don't really feel rested the next day. Question is, why is one better than the other? Also is too much bed rest bad for post concussion syndrome and it's healing?

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.

Is there any delay in recovery if you stay in bed most days? Does it matter?

How would you be able to tell if you are improving ? There is not a magic number of days of bed rest that will cause recovery. Good blood circulation is good for recovery. Plus, bed rest is draining emotionally.

Very few concussion specialists recommend bed rest, if any even do.

That really depends on how long ago your injury was. I slept a lot after mine, all but a few hours, then as I became more aware after about a week I was awake longer.

You need to rest with no stimulation; light, sound ect. If you're fatigue is bad have a nap. If not just think or mediatate. Calm your senses, comfort your body, rest your mind.

Make sure you also get some fresh air, a walk, and a stretch. These activities will become more frequent as you are well enough, but dont push yourself to hard. Your body is working hard trying to get better.

I wouldnt worry about old fashioned notions of bed rest meaning being confined to the bed.