Dreams may have an important physiological function

November 12, 2009 by Lin Edwards A child sleeping (Sleep)

A child sleeping. Image: Alessandro Zangrilli, via Wikipedia.

(PhysOrg.com) -- Dreams have long been assumed to have psychological functions such as consolidating emotional memories and processing experiences or problems, but according to a Harvard psychiatrist and sleep researcher the real function may actually be physiological.

According to Dr J. Allan Hobson, the major function of the (REM) sleep associated with dreams is physiological rather than psychological. During REM sleep the brain is activated and "warming its circuits" and is anticipating the sights, sounds and emotions of the waking state.

Dr Hobson said the idea explains a lot, and likened it to jogging. The body does not remember every step of a jog, but it knows it has exercised, and in the same way we do not remember many of our dreams, but our minds have been tuned for conscious awareness.

Hobson said dreams represent a parallel consciousness state that is running continuously, but which is normally suppressed while the person is awake. Dr Mark Mahowald, a neurologist from Hennepin County Medical Center, in Minneapolis, said most people studying dreams have started out with fixed ideas about the psychological functions of dreaming, and try to make dreaming fit these ideas, but the new study makes no such assumptions.

In evolutionary terms REM sleep seems to be relatively recent, and has been identified in humans, other warm-blooded animals, and birds. Earlier studies have suggested it appears early in life, in the third trimester in humans, and research has produced evidence the brain of the may in a sense be "seeing" images long before its eyes are opened, so the REM state appears to help the brain build , especially in the visual areas.

This does not mean dreams have no psychological meaning, since they do at times reflect current problems, anxieties and hopes, but people can read almost anything into dreams. A recent study of more than one thousand people at Carnegie Mellon University in Harvard, showed that there were strong biases in how people interpreted dreams. So, for example, subjects attached more significance to negative dreams about people they disliked and to positive dreams about people they liked.

Research on lucid dreams has suggested that only 20 percent of dreams are about people or places we know, and most images are unique to a single dream. Lucid dreaming is the ability to watch a as an observer without waking up, and Dr Hobson finds support in lucid dreaming for his argument for dreams as a kind of physiological brain exercise. A study co-authored by Hobson and published in the September issue of the journal Sleep reported that elements of both REM and waking were apparent in lucid dreaming, especially in the frontal areas that are quiet during normal dreams. According to Hobson, this suggests there are two systems, which can be running at the same time.

The potential applications of the research may be a deeper understanding of conditions such as schizophrenia, which is categorized by imaginings that may be related to abnormal activation of a dreaming state.

The paper was published last month in the Nature Reviews Neuroscience journal.

More information: and dreaming: towards a theory of protoconsciousness,
Nature Reviews Neuroscience, 10, 803-813 (November 2009); doi:10.1038/nrn2716

© 2009 PhysOrg.com


print this article email this article download pdf blog this article bookmark this article     Stumble it Digg this share on Facebook retweet share on Reddit add to delicious
Rate this story - 3.9 /5 (27 votes)

Rank Filter

Move the slider to adjust rank threshold, so that you can hide some of the comments.


Display comments: newest first

  • teledyn - Nov 12, 2009
    • Rank: 4 / 5 (5)
    In the Anime "End of Evangelion" it is said that dreams do not replace reality, dreams EXTEND reality. The early 20th century mystic writer P.D.Ouspensky also insisted that the dream state does not vanish upon waking, but remains as a background, masked by our consciousness in the same way that the morning sun scatters light that hides the always-present starry skies.
  • frajo - Nov 12, 2009
    • Rank: 4 / 5 (1)
    has been identified in humans, other warm-blooded animals, and birds.

    "has been identified in humans, birds, and other warm-blooded animals" would have made sense.
  • superhuman - Nov 12, 2009
    • Rank: not rated yet
    And where is evidence to support his theory?
  • defunctdiety - Nov 12, 2009
    • Rank: not rated yet
    And where is evidence to support his theory?


    Sensory deprivation. Look into it. Differing techniques have been used in everything from meditation to interrogation. In the meditative application, you are conscious (awake) but have 0 input from your senses i.e. floating in high saline warm water, in a sound proof, blacked out tank. Read user accounts of the experience (I would recommend Joe Rogan's :P), read research on it in all it's forms. Very intriguing stuff.

    Also, I think about anyone who's take hallucinogenic substances (psilocybin, etc., which theoretically activate these parts of brain activity w/ the senses intact) would affirm such theories.

    Not super scientific stuff, but infinitely more interesting, IMO.
  • JRDarby - Nov 12, 2009
    • Rank: not rated yet
    I marvel at how some people cling dogmatically to materialism the same way others cling to their religious beliefs. While I appreciate the research (as I appreciate any experimental research), I can't help shake the feeling the experimenter is trying very hard to eschew any notion that dreaming may have an important, non-physical/non-physiological component, purpose, or function that falls outside the purview of scientific orthodoxy.
  • frajo - Nov 12, 2009
    • Rank: not rated yet
    the experimenter is trying very hard to eschew any notion that dreaming may have an important, non-physical/non-physiological component, purpose, or function that falls outside the purview of scientific orthodoxy.

    Per definitionem no object outside of the realm of scientific reasoning can be studied by science. The intersection of science and metaphysics is empty.
  • fuzz54 - Nov 12, 2009
    • Rank: not rated yet
    I marvel at how some people cling dogmatically to materialism the same way others cling to their religious beliefs. While I appreciate the research (as I appreciate any experimental research), I can't help shake the feeling the experimenter is trying very hard to eschew any notion that dreaming may have an important, non-physical/non-physiological component, purpose, or function that falls outside the purview of scientific orthodoxy.


    There would be no way to test the hypothesis that dreaming has a function that falls outside the purview of scientific orthodoxy.
  • superhuman - Nov 13, 2009
    • Rank: not rated yet
    And where is evidence to support his theory?

    Sensory deprivation. (...) hallucinogenic substances...


    I am well aware of the effects of both but I fail to see how it is supporting the theory that dreaming is a practice as opposed to dreaming as a random noise, dreaming as refreshing of memories and so on.
  • defunctdiety - Nov 13, 2009
    • Rank: not rated yet
    I am well aware of the effects of both but I fail to see how it is supporting the theory that dreaming is a practice as opposed to dreaming as a random noise, dreaming as refreshing of memories and so on.

    My mistake, I thought you were asking for evidence to support the theory of P.D.Ouspensky, as put forth by teledyn:
    "insisted that the dream state does not vanish upon waking, but remains as a background, masked by our consciousness"

    Which Hobson also stated in the article: "Hobson said dreams represent a parallel consciousness state that is running continuously, but which is normally suppressed while the person is awake."
  • Lumina_Sprite - Nov 15, 2009
    • Rank: not rated yet
    It's wonderful to find that people actually exist that are not idiots. I'm so glad that people have open minds, here. It's so refreshing, compared to the dull high school melodrama that I am forced to wade through daily. This site is a god send.

    I happen to feel that dreams as a function of mental house cleaning, organizing thoughts and feelings, is a rather scientific approach, and dreams could quite possibly have a deeper spiritual meaning. Not to dogmatically cling to any spiritual beliefs, or anything...just musing...
  • frajo - Nov 15, 2009
    • Rank: not rated yet
    I happen to feel that dreams as a function of mental house cleaning, organizing thoughts and feelings, is a rather scientific approach, and dreams could quite possibly have a deeper spiritual meaning. Not to dogmatically cling to any spiritual beliefs, or anything...just musing...

    The problem with your "deeper spiritual meaning" is that it lacks the quality of falsifiability which is indispensable for scientific reasoning.
    In a non-scientific context it could make sense, of course.
  • Fabian - Nov 20, 2009
    • Rank: not rated yet
    So it may be that dreams are a result of the brain being placed on "idle" like a revving car at an intersection waiting to move. The brain never stops processing information, real or imagined, twenty four hours a day. I'm interested in knowing how the researcher could even develop an experiment to verify this.

November 12, 2009 all stories

Comments: 12

3.9 /5 (27 votes)
  • Stumble this up

  • Digg this

  • share this

  • hide
  • Related Stories




  • hide
  • Relevant PhysicsForums posts

  • nesfatin
    created Nov 22, 2009
  • Obsessive Compulsive Disorder
    created Nov 20, 2009
  • West's zone 2 starling resistor respiratory physiology
    created Nov 18, 2009
  • 50-0-50 rule
    created Nov 18, 2009
  • More from Physics Forums - Medical Sciences

Other News

Multitasking may be Achilles heel for hepatitis C

Medicine & Health / Research

created 9 hours ago | popularity 5 / 5 (1) | comments 0

(PhysOrg.com) -- Hepatitis C, a formidable virus that affects 130 million people worldwide, is nursing some pretty impressive bruises. By knocking out sections and subsections of one of its proteins, scientists reveal weak ...


Gene therapy improves vision

Gene therapy improves vision

Medicine & Health / Research

created 10 hours ago | popularity 5 / 5 (2) | comments 0

German scientist Paul Ehrlich found what he coined the "magic bullet" in the early 20th century upon developing the world’s first effective treatment of syphilis.


Tissue tension regulates tumor progression

Medicine & Health / Cancer

created 10 hours ago | popularity not rated yet | comments 0

(PhysOrg.com) -- UCSF scientists have shown for the first time that the rigidity of a tissue can induce cancer. The research team identified an enzyme that is crucial for regulating tissue stiffness and demonstrated that ...


Fat around the middle increases the risk of dementia

Medicine & Health / Neuroscience

created 14 hours ago | popularity not rated yet | comments 0

Women who store fat on their waist in middle age are more than twice as likely to develop dementia when they get older, reveals a new study from the Sahlgrenska Academy.


Measured -- The time it takes us to find the words we need

Medicine & Health / Psychology & Psychiatry

created 12 hours ago | popularity 3.3 / 5 (3) | comments 0

(PhysOrg.com) -- The time it takes for our brains to search for and retrieve the word we want to say has been measured for the first time. The discovery is reported in a paper published in the Proceedings of the National Ac ...