The times I had this experience with depression and feeling empty headed etc was when I was working off-shore. We were isolated at sea for 8-10 months per year and it was 2-3 months stretches in one go (with only 1-2 days in between). I wasn't able to smoke weed back then and there was no Internet out there. I didn't know about cabin fever back then but only learned later that this must have been what it was.

But I strongly agree that smoking for many weeks/months every day could sure trigger a lot of side effects.

Isolation/quarantine right now is very different (I got Internet, and the problem is there is actually too much choice of what I could read, watch or study).

edit: N.N. Taleb talks about his concept of "balancing extremes", I'm very much a believer of this life style.