OK after reading all the posts on this thread I have to wonder if Knitting releases something like Serotonin? I wonder because I feel the same way as many of you do in regards to relaxation.
I have both Migraines and mild OCD,(obsessive compulsive disorder). Because of this I find that repetitive actions are soothing, they are said to aid in the stimulaton of the types of chemicals that lower aggressive and anxious emotions.
Because of the OCD I cannot sit and watch TV, just can't do it. I have to have something to do, it used to be Jigsaw puzzles but I got bored with that as I can to a 1000 peice in a little more than an evening.
When I started Knitting it was not with yarn. I used to knit with wire, I made ChainMaille, yes as in armour.
See, I am a Mechanic by trade and preference so I understood wire, yarn was a mystery to me. (As are most of the female arts, I am a horrible tomboy still in my 30's) But you cannot sell/give away as many peices of armour as you might think.
So I switched to yarn and have been happily dragging around a knitting bag ever since.
This has shocked many people as I never owned a purse in my life and this looks mighty similar.
Knitting has given me a shared common interest with my grandma and my mom, and gives my son and I something to do together while watching TV. He is 13 and just learning.