If we do any reading about dreams we see that a lot of emphasis is placed on similarities in all dreams rather than particular dreams. We also see that studies look at how we dream or "consciously experience sleep" through the different stages of sleep and the brain activity that these create. And we explore whether sleeping is a form of perception of the environment or mental imagery rising up from the sleeping mind.
From great contemporary thinkers like Freud to modern sleep studies, dreams seem to play a huge role in theories and findings about the brain when it is "at rest". Naturally that opens the door to the question of whether the brain is ever at rest or not. After all, we know that sleep is divided into stages based almost entirely on the brain activity that defines the separate stage.
"I never dream," is something many people say, and that means one thing: They are dreaming but their sleep is so healthy and sound that their dreams do not wake them.
As we drift through the stages of sleep each evening, our brains are full of activity that we can describe as brain waves. Given names like Alpha, Beta, Gamma and so on, these waves tend to occur at specific points in sleep. Called stages, they run from number one through five. The stages occur in "cycles", but are not continuous in pattern (i.e. 1,2,3,4,5,1,2…) Instead, truly healthy sleep starts with one and moves through to four, then cycles backwards to one again. It then enters stage five or what is more commonly known as REM or rapid eye movement sleep.
Exiting REM we enter into stage two and then continue the same process several times throughout the night. To reach REM does not take hours, and most of us hit it at around 90 minutes into sleep. Our first cycle of REM at night is the shortest and then extends to longer periods as sleep progresses.
Thus, the need for at least eight hours of sleep each evening in order to enjoy longer periods of healing REM. When we sleep restlessly, waking and rising, it actually harms health.
Stage one sleep has you drifting into sleep; stage two is when your breathing changes and your heart rate slows. Stage three sees you move between light and deep sleep, and stage four is deeper and is when issues like sleepwalking will occur due to the brainwave activity.
REM is when you will dream and experience a lot of brain activity. Interestingly enough, though your brain is very active at this point, your muscles become relaxed to the point of being nearly paralyzed. All of your voluntary muscle movement is disabled at this point and your body is in a state of deep relaxation. The brain, though, is buzzing away, processing all that is passing through.
What is happening? As one study has pointed out, it can be very difficult to determine this because waking the REM sleeper when it is clear they are dreaming allows only their blurry report of the dream. However, scientists have made progress, with one major study saying, "Converging evidence from multiple fields of study … support the notion that dreaming may be closely related to imagination, where brain activity presumably flows in a 'top-down' manner. Viewing dreams as a powerful form of imagination can help explain many of their unique features, such as sudden transitions, uncertainty about people and places, poor subsequent recall, disconnection from the environment, and offers testable predictions for future studies."
We cannot control or even influence dreams, but we can make plans for giving our brains what they need through many hours of restful sleep and the nutritional support needed to enhance mental function.
NCBI. Dreaming and the brain: from phenomenology to neurophysiology. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2814941/