An Interesting Theory
Here's a post from Derren Brown's blog, titled "We need to dream regularly as a vital release for our emotions":
“An essential function of dreaming is psychological stretching, a kind of yoga for the soul: gently expanding, releasing, opening, and softening.” Like stretching a muscle, a dream can release emotional pain, tightness from earlier in the day - or even hurt from childhood. Dreaming provides “a poetic cushion” for our sharply literal lives, he says.
I'm not sure about the use of the word "vital", but I think it's obvious that dreams do help tremendously. By the way, I can't wait to ...