Neurophilosophy

Sleepy brain waves predict dream recall

THE patterns of brain waves that occur during sleep can predict the likelihood that dreams will be successfully recalled upon waking up, according to a new study published in the Journal of Neuroscience. The research provides the first evidence of a ‘signature’ pattern of brain activity  associated with dream recall. It also provides further insight into the brain mechanisms underlying dreaming, and into the relationship between our dreams and our memories.

Cristina Marzano of the Sleep Psychophysiology Laboratory at the University of Rome and her colleagues recruited 65 students, selected on the basis of their sleeping habits. All of them had a regular sleep ‘routine’, going to bed at around the same time, and sleeping for an average of seven-and-a-half hours, every night. For the study, the participants slept for two consecutive nights in a sound-proof, temperature-controlled room in the lab. They were left to sleep uninterrupted on the first night, so that they would get accustomed to the new surroundings. 

On the second night, the researchers used electroencephalography (EEG) to measure the participants’ brain waves while they slept, and woke them up during specific types of sleep. Sleep occurs in five distinct stages, each characterized by a distinct pattern of brain waves, and most dreaming occurs in the rapid eye movement (REM) stage. Some of the participants were woken up during REM sleep, as determined by their brain waves, while others were woken up during stage 2 sleep. Soon after being woken up, they were asked filled out a ‘sleep and dream diary’, giving details of whether or not they dreamt, how many dreams they had and, if they could remember, the contents of any dreams they had.

The researchers found that they could predict successful dream recall from the brain activity patterns recorded just before awakening. Of the participants woken  up during REM sleep, those who exhibited more low frequency theta waves in the frontal lobes were more likely to remember their dreams than those who did not. Dream recall after waking from stage 2 sleep was associated with a reduction in higher frequency alpha waves recorded from the right temporal lobe. The predictions were most accurate when based on the recordings of activity that occurred about five minutes before awakening.

We know that the brain processes newly acquired information while we sleep, and although the function of dreaming is unknown, some researchers believe that it plays an important role in memory consolidation. Our dreams may be a manifestation of the brain activity associated with ‘replaying’ the day’s events, so dream recall can be thought of as a form of episodic, or autobiographical, memory. 

Indeed, previous studies have shown that brain waves in the frontal and temporal lobes can predict encoding and subsequent recall of episodic memories, and that they can even be used to distinguish between true and false memories. We also know that oscillatory activity in the frontal and temporal lobes plays an important role in memory formation, and that interactions between these two regions are necessary for long-term memory storage.

The new study shows that dreaming and dream recall appear to involve the same brain wave patterns as encoding and retrieval of episodic memories. This suggests that the brain mechanisms underlying memory encoding and retrieval during sleep are the same as those during waking hours.  


Marzano, C., et al. (2011). Recalling and Forgetting Dreams: Theta and Alpha Oscillations during Sleep Predict Subsequent Dream Recall. J. Neurosci. 31: 6674-6683 DOI: 10.1523/JNEUROSCI.0412-11.2011.

Comments

  1. #1 natselrox
    May 10, 2011

    Fascinating post as usual, Mo!

    Quite a lot of research has been done regarding the correlation of theta waves and enhanced synaptic plasticity, I think. What does it possibly say about the laying down of memories at the molecular level? And in which direction does the causal arrow lie in this? Is it that better memory formation causes theta waves? Or is it that the synchronisation is somehow conducive to the formation of new memories with some degree of predictive power (as said in this paper)?

    Thanks! :)

  2. #2 russell
    May 11, 2011

    interesting. this is somewhat off topic, but does anyone know if there is a significant correlation between waking brain states (delta&theta waves) and information retention. i heard through a guy named bruce lipton that infants spend the majority of their time in these states of brain activity which allows them to acquire new information so readily.

    i`m sure it has much to do with the increased synaptic plasticity of younger mammals as well though, but perhaps there is a correlation between higher amplitude lower frequency waves, and synaptic plasticity? any ideas would be much appreciated…

  3. #3 Adam
    May 11, 2011

    impact on sleep deprivation caused by covert criminal activity sponsored governments corporate organized crimes, not different from the one in Iraq, only the method is. in the so called free world. through the use of microwave, direct energy weapon & other means. Just a matter of time before it becomes public knowledge.

    Symptoms. heat burn, reduction and loose of sense including hearing, eye sight, sense of smell, repeated other loses occur heart and other organs are affected.
    A slow form torture and assassination.
    No Terror No Torture just Truth.

  4. #4 Ink Cartridge Sam
    May 16, 2011

    Interesting. I’ve found that even one or two drinks before bed will drastically reduce my chances of remembering my dreams.

  5. Nothing natural is “manicured”. It’s your choice, or at least the result of decisions you’d otherwise claim to have made. You’re describing your normative existence, nothing more, nothing less. If you thought of yourself as an aspect of history you might ask how your social life became so denuded of variety; bounded by preconceptions -by others’ ideas rather than by your own experience. It originates in a phobia of subjectivity I guess..

  6. #6 ursa major
    May 21, 2011

    Curious. It is somewhat hard to describe, but for many years I have noticed that dreams I can recall feel different from dreams which I can not remember when I awaken. Guess it is those low frequency theta waves.

  7. #7 David Brains
    July 7, 2011

    Very interesting research! I have always been interested in sleep and dreaming myself, trying to write down my dreams as soon as I wake up for better recall.

    An interesting phenomenon is the emergence of new ‘alarm clocks’ that monitor brain-activity and only wake you up when in a desired state of brain-wave patterns. Exploiting this concept could be potentially very interesting as a dream-recalling tool!

  8. #8 David Moody
    July 27, 2011

    An unsubstantiated (but not yet disproven) theory claims that dreaming creates a false sense of security. That is to say: that after lose of consciousness in the later stages of sleep, some unspecified part of the mind begins to panic with the lose of awareness and that a higher centre in the brain creates the dream images, which supposedly makes us believe we are awake, which may explain why during REM sleep, a change in brainwave activity that mimics that of a person who is awake is seen.
    On a personal note, I believe that the dream process may actually begin before the change in brainwave activity, which is why we can never really remember when a dream began.

  9. #9 jb
    August 7, 2011

    This gives me an idea for a product: an alarm clock that wakes you up (within certain constraints) at times when you are highly likely to remember your dream(s). If we spend 3+ hours per night dreaming, might as well ensure we remember it.