Why and how we dream is still not fully understood. There are many different schools of thinking about dreams ranging from philosophical theories to empirical investigations of specific brain processes involved in dreaming.
Phases of sleep
There are five phases to the sleep cycle ranging from wake, relaxed wakefulness, light sleep, deep sleep and rapid eye movement (REM) sleep. Everyone cycles through the different sleep phases. The most restorative sleep is deep sleep.
Dreaming and sleep phases
You can dream during any of the sleep phases, but the most vivid dreams occur during REM sleep. During this time, signals to the spinal cord are inhibited by an area of the brain called the pons. This stops us from acting out our dreams. The brain regions activated during REM sleep are those that are associated with learning. Studies have shown that depriving people of REM sleep inhibits their ability to recall material that they have learnt.
The utility of dreaming
Although it is not definitively known why we dream, there are a number of hypotheses. A key one being that it is a method used to help us learn by consolidating new information with older information. The Activation-Synthesis Model of dreaming proposes that certain circuits in the brain become activated and the brain attempts to synthesize this activity, finding meaning in these signals. Dreams are the outcome. It has been argued then that dreaming is a deeply creative process that can produce novel ideas and configurations of information. Although most may end up being nonsensical, some may end up being highly useful to us in some way.
Other theories about dreams range from them being a manifestation of deep unconscious desires (the psychoanalytic theory of dreams), to dreams not serving any real function at all. Although advances in neuroscientific methods of tracking brain function and activity have helped progress theories, there is still a lot more to be discovered.
Author: Dr Sula Windgassen
See also: sleep capsules