Dreams are the one aspect of sleep that has fascinated mankind for centuries. They have been a discussion topic for a host of different groups and systems, from religious to psychological. Yet for all of the focus that dreams have garnered throughout the years, it still remains a mysterious component of a person's overall sleep cycle.

How Dreams are Studied

Although the content and purpose of dreams is something that has yet to be definitively defined, there are aspects of the dreaming process that have been deciphered through the process of oneirology; that is, the scientific study of dreams.

In essence, the purpose of oneirology is to determine specific correlations between the process of dreaming and how the brain has been known to function. This would include understanding the ways in which the brain's functionality during the dreaming phase could be linked to the formation of memories and various mental disorders. This process merely concerns itself with studying the overall process of dreams, as opposed to trying to interpret the meaning of dreams through the psychoanalytical process of dream analysis.

Through the process of oneriological study, it has been determined that dreams chiefly occur during the REM (or Rapid-eye Movement) stage of sleep. This particular stage of the sleep cycle has been marked by an instance of brain activity that is comparable to the brain activity that occurs during a state of wakefulness, if not even higher. It has also been determined that dreaming can occur during other stages of the sleep cycle, but those particular dreams tend to be significantly less vivid. It has been shown that people that are awakened during the REM phase of the sleep cycle will be more likely to remember the dream.

On average, the typical person will have three to five dreams a night. Typically, the length of the dream is variable in nature, as it can range anywhere between a few seconds to around 20 to 30 minutes. That said, it has been shown that the dreams tend to last longer as the night progresses, something that would seem to correlate with the notion that REM sleep also lengthens as a person's interval of sleep progresses during the night. It has been thought that a person that would live an average lifespan would spend roughly six years dreaming; this number breaks down to average about two hours per night.

Dreams and Neurobiology

Additional data regarding dreams has been culled through the process of neurobiology; that is, the study of the body's nervous system. For instance, it has been determined that during REM - the stage of sleep where most dreaming occurs - the release of the following neurotransmitters is suppressed:

  • Norepinephrine - This is the neurotransmitter that is most responsible for concentration.
  • Serotonin - This is the neurotransmitter that is thought to contribute to feelings associated with well-being
  • Histamine - This is the neurotransmitter that plays a key role the body's inflammatory response.

Activity pertaining to the prefrontal cortex has determined to play a role in how a person may feel during the dreaming process. In essence, the prefrontal cortex is responsible for regulating brain functionality as it pertains to logic and planning. During most dreams, the person that is dreaming is unaware that they are dreaming, regardless of how nonsensical the dream environment may be. The reason for this is due to a decreased level of activity produced by the prefrontal cortex during the dreaming process.

That said, this process has not been able to determine whether or not there is a single point of origin within the brain that generates dreams, or if multiple portions of the brain work in concert to produce the dreams.

Theories Related to the Dream Process

While there has not been any definitive understanding that pertains to the content and purpose of dreams, there have been a few theories as to how and why they come about. The theories are essentially divided into two camps: Neurologically and psychologically.

The neurological theories are tied to how the brain has been shown as being active during REM sleep. One theory, the activation synthesis theory, suggests that signals that are interpreted as dreams have their genesis in the brain stem during REM sleep. This theory is tied to notion that circuits found within the brain stem become activated during REM sleep; this activation in turn activates areas in the limbic system that have been shown to link to sensations, emotions, and memories. Another theory is continual-activation theory. In this theory, it is thought that the process of dreaming is the product of the brain activating and synthesizing data tied to memory stores; every time the brain activates to synthesize data, dreams are triggered. A third neurological-based theory ties to the process of defensive immobilization, which states that REM sleep is an evolutionary progression of the tonic immobility reflex in animals (that is, the defense mechanism that enables an animal to play dead). Other theories tied to neurology correlate dreams as being excitations of long-term memory, a way for the brain to strengthen semantic memories, and as a means to dump out excessive sensory data.

Psychologically speaking, one prominent theory ties dreams to a two-step process that ultimately works to improve the brain's capacity to meet various emotional needs during wakefulness. Several theories claim that dreams are merely random by-products of the REM process and that they are without any actual purpose or function. These theories point to the fact that people can function properly without remembering any of the dreams that, as the one theory suggests, would prepare a person emotionally for the upcoming day. Other psychologically-rooted theories pertaining to dreams relate to dissociated imagination, a discharge of various emotional arousals that were not met during the day, and to provide a sense of satisfaction to repressed part of the mind without interfering with the thoughts that would otherwise be exhibited by the conscious mind.

All theories aside, why we dream and where dreams come from still remain a mystery. And until the mystery is unlocked, it will undoubtedly remain a subject that will be researched extensively.