In reading about dream recall, to my understanding, to be able to recall effectively, you have to awaken during rem sleep. On some days my recall is great (4 dreams per night) other nights I can't recall one, but each time I awaken and do remember I would quickly jot down bits and pieces so I don't forget.

I read somewhere that the reason your supposed to jot them down is because the brain tends to erase the old dream upon entering a new stage of rem. Is that correct? I'm puzzled because I can still recall dreams that I had 4 months ago.

What is the longest time you could recall a dream from?