Dreams are ever-present excitations of long term memory, even during waking life. During waking life an executive function in the brain interprets long term memory consistent with reality checking. Thus, we have no control over dreams when we are asleep but can control much of our day dreaming, because part of our brain is controlling the scenario whilst clock-watching. On average, humans (sleep)dream for about 2 hours a night, due to heightened brain activity or REM (not the band). Some of us remember them some of us don�t, but in reality our dreams are very very long drawn out �stories� and our awaking memory recalls only a snapshot of the story � mainly the interesting bits. In daydreaming you control the �dream� by consciously creating nonsensical or fanciful scenarios and stories, where in sleep it is subconscious long term memory recollection.