The relation of eye movements during sleep to dream activity: An objective method for the study of dreaming. Dement & Kleitman (1957)

SLEEP  It is an interesting topic and it has been usually studied by medicine.  The better way to investigate this issue, is using electroencephalography (EEG) measuring brain activity during sleep.  This usually gives an idea of the “structure” of sleep during the night.

SLEEP 1.NREM SLEEP (9-130 mins) Each stage STAGE 1: (hypnagogic stage) Transition state between being awake and sleeping. Eyes move more slowly Muscle activity and heart rate slow down. Light sleep where you can be awakened easily Relaxation stage  drowsiness STAGE 2: Movement stops Brain waves become slower with an occasional burst of rapid brain waves. At this point, the body prepares to enter deep sleep.

SLEEP STAGE 3 - Extremely slow brain waves (delta waves) -Combined with smaller, faster waves called theta waves. STAGE 4 - Deepest sleep. - No eye movement or muscle activity - Brain produces more delta waves than theta waves. - In Stage 4, some may experience sleepwalking or night terrors.

REM SLEEP (rapid eye movement) STAGE 5 - Breathing becomes more rapid - Eyes move rapidly - Muscles are temporarily paralysed. (to protect from acting out)  Heartbeat may increase and muscles may experience occasional muscular twitches. - REM usually takes place 90 minutes after falling asleep.  Normal sleep cycle: Stages 1, 2, 3, 4, 3, 2, REM

BACKGROUND AND CONTEXT  Dreaming and sleep are closely related, but only recently it’s been studied scientifically.  It is a very interesting topic, and has caught the attention of many scientists.  Sleep deprivation  one of the ways of studying sleep.

BACKGROUND AND CONTEXT  Scientific study of dreams  physiological variables using a reliable scientific method to determine exactly when dreaming occurs.  Self report  there is no other way of proving dreaming occured.  Self reports + physiological techniques to measure phenomena  reliable and objective

BACKGROUND AND CONTEXT  Aserinsky + Kleitman  first to study relationship between REM and sleep  They discovered that high dream recall in participants woken up during REM.  They confirmed the relationship between REM + SLEEP + DREAMING

BACKGROUND AND CONTEXT  They also discovered that there was a cyclic process  depth of sleep changed during the night

AIM AND NATURE  This study shows the results of a rigorous testing of the relationship between eye movement and dreaming.  Hypotheses: 1. There is a significant relationship between REM/NREM sleep and dreaming, such that (based on previous research). REM sleep is associated with dreaming and NREM, isn’t.

AIM AND NATURE  2. There is a significant positive correlation between the subjective estimate of the duration of dreams, and the length of eye movement period prior to awakening.  3. There is a significant association between the pattern of eye movement and the content of the dream. Eye movement reflects the visual experience of the dream.

METHOD / DESIGN  7 adult males / 2 adult females  Studied under controlled lab conditions  1 night in the sleep lab being woken at various intervals  Physiological recordings were made of:  Changes in corneoretinal potential fields as the eyes moved  Brainwaves (as a criterion of depth of sleep)

METHOD / DESIGN  Two or more electrodes were attached near the eyes  Two or three attached to the scalp.  Participants were woken by the ringing a doorbell  near the bed for them to wake up.

METHOD / DESIGN  Participants had to speak into a recording device near the bed and say:  Whether or not they had dreamt  If they could, relate the content of the dream  No communication between participants and the experimenter until it had been judged that the participant had been dreaming.

How did they know participants had really dreamt?  They had to give a coherent, fairly detailed description of dream content.  Only then the experimenter could enter the room and ask for details.  Participants didn’t know if they were woken from a REM or NREM sleep.

RESULTS/ FINDINGS  REM sleep basically had low voltage relatively fast EEG pattern.

RESULTS/ FINDINGS  In between REM periods  EEG indicated deeper sleep  They were either  High voltage  Slow activity  Or frequent No REMs were observed during the initial moments of sleep

RESULTS/ FINDINGS  REM uninterrupted periods lasted between 3-50 minutes (mean 20)  They tended to increase the later in the night they occurred  The eyes didn’t move with a constant pattern  they occurred in bursts of 1, 2 to 100 movements  A single movement lasted seconds and followed by a fixation pause of varying duration.

RESULTS/ FINDINGS  The REM periods occurred quite frequently during the night  average every 92 minutes.  Awakenings during the night: Despite the awakenings, sleep was similar to uninterrupted sleep. HOURS% First 2 hours21 Second 2 hours29 Third 2 hours28 Fourth 2 hours22

RESULTS/ FINDINGS HYPOTHESIS 1  Participants uniformly showed a high incidence of dream recall following REM awakenings, and a low incidence following NREM awakenings.  When REMs stopped, the incidence of dream recall dropped dramatically.  Within 8 mins after REM ended  in 17 awakenings  5 dreams were recalled  Within more than 8 mins after NREM  132 awakenings  6 dreams were recalled.

RESULTS/ FINDINGS  Participants were more confident they hadn’t dreamed, after NREM  When aroused during deep sleep  they were confused and they felt they must’ve been dreaming but they didn’t remember the dream.  When participants couldn’t recall a dream following REM sleep, this was usually in the first two hours.

RESULTS/ FINDINGS  HYPOTHESIS 2 Participants were woken after 5 or 15 mins after REM, and based on their recall of the dream, they had to decide which was the correct duration.  All but one could do this accurately  Significant correlation between minutes of REM and lengths of dream narratives (words)

RESULTS/ FINDINGS  HYPOTHESIS 3  it was hard to know the direction in which Ps were looking when dreaming.  They were woken up as soon as a pattern of eye movement persisted for at least a minute.  Mainly vertical  Mainly horizontal  Vertical and horizontal  Very little or no movement.

RESULTS/ FINDINGS  Of 35 awakenings  only 3 periods of only vertical or only horizontal.  There were several dreams and usually eye movement corresponded to what was happening in the dream.  In participants with mixed movements  usually they were looking at a moving object close to them.

CONCLUSIONS  Each of the 9 participants had regularly REM periods during the night.  As predicted: 1. High incidence of dream recall ocurred when participants were woken up after REM. Low for NREM. 2. When a series of awakenings ocurred either 5 or 15 minutes after REMs had began, participants judged the correct dream duration very accurately. 3. The pattern of REMs was related to the visual imagery of the dreams. Recording REMs during sleep  objective measure of dreaming.

EVALUATION: Methodological issues  Beaumont  being woken from NREM dream may lead to forgetting more than with REM  In REM sleep the brain is more active  This could be a major confounding variable that could make all these results to be questionable easily.

 Herman  there is no considerable difference in dream report between REM and NREM.  Foulkes: saying that REM=dreaming and NREM = non dreaming  oversimplification  Although only 5-10% of NREM sleepers reported dreaming, 70% could report dream like impressions.  Besides, dreaming is also established to occur during the hypnagogic period and daydreaming.

Theoretical issues  One of the great questions of psychology is “is dreaming useful?/necessary?”  Should sleep be seen as active or passive?  Sleep is an active process  not a consequence of neuronal fatigue.  The brain of a sleeping person is almost as active as the one from a person who’s awake.  SLEEP IS AN ACTIVE PROCESS

Theoretical issues  Evidence has been been found for the relationship between REM sleep and dreaming  rem rebound phenomenon.  REM rebound: When people are deprived from REM sleep, the next night they “make up” for it. Compensation.  Dement: when participants were deprived from REM sleep  irritable, nervous, unable to concentrate, paranoid, hallucinations, etc.  These symptoms were very possibly, consequence of Dement’s own expectations  he told the Ps that this experiment could have consequences and had an available psychiatrist.

Theoretical issues  Dement replicated the study and found no evidence for psychiatric impairment in REM deprived Ps.  He also found evidence for the REM rebound  Then, possibly REM and dreaming are the most important functions of sleep.

Subsequent research  1990’s  There was a change in the vision of dreaming and REM.  Dreaming appeared to be a continuous process that also occurred during NREM periods.  NREM dreams  shorter and more rationally constructed.  REM dreams  more emotional and more detailed.

Subsequent research  Researchers questioned if really REM was necessary for dreaming to take place  At some point, REM sleep was linked to a brain structure called PONS (research with kittens)

Subsequent research  But, evidence: people with problems in PONS dreamt anyway.  Or people who said they had never dreamed, but had an intact pons, even though they went through REM phases.  But they had lesions in other brain structures. What is clear for this research  Dream takes place independently of REM and the pons.

Subsequent research Hobson’s Activation-Synthesis model: “REM-ON” area located in the pontine reticular formation  ACTIVATION  REM sleep  This prevents most sensory information from reaching the brain.  The switch from the motor cortex is switched off, causing the person to be paralysed during REM sleep.  Other structures associated to memory and emotion are activated

In summary  When REM sleep occurs:  REM-ON area: Activation (ON)  Motor cortex  OFF  Memory and emotion structures  ON (probably hippocampus and amygdala)

Subsequent research  Dreaming occurs when these systems activate simultaneously and are syntethized  similar to a waking brain  In a waking brain SENSORY INFORMATIO N MOTOR INFORMATION EMOTIONAL INFORMATION MEMOR Y SENSE OF REALITY This information is presented in an ordered way when we are awake

Subsequent research  In dreams  information doesn’t follow a logic order  weird dreams  The internal processes involved in dreaming are random.  Dreams normally involves activity from the visual and motor systems.  Many dreams could be understood based on body experience  erotic dreams, flying, etc, related to certain organs.

Subsequent research  Reverse learning (Crick&Mitchison)  we dream in order to forget.  A complex associational network  overloaded of incoming information  creation of false thoughts.  These thoughts might be outdated but persistent.  REM sleep could be erasing those thoughts (unlearning)

Subsequent research  Crick & Mitchison  trying to record our dreams isn’t a good idea. They are ideas we’re trying to get rid of!  This model only applies to bizarre dream content. And what about narrative?  This is better understood as dreaming to reduce fantasy or obsession.

Subsequent research  The activation-synthesis model refers to the where but not to the why or what for.  Here is where psychological (psychodynamic) perspectives come into play  Freud

Freud’s theory of dreams  1900  The interpretation of dreams (S.Freud)  “Todo sueño es cumplimiento de deseo”.  Dream usually manifest certain ideas or experiences that weren’t elaborated during the day (restos diurnos)  2 types of content:  Manifest content: the story or narration itself  Latent content: the meaning (underlying)

Applications and implications  In animals, REM sleep may have evolved to access repeatedly the information useful for survival (location of food, etc)  To mantain sleep  movement had to be suppressed (motor neurons) otherwise you wake up!  Eye movement wasn’t enought to wake up, so there is still access to visual information that, combined with past experience  strategy for behaviour.  It might be adaptive

Applications and implications  In humans…  It could be that the crucial information for survival is the basic information in the unconscious.  We have language, animals don’t. Information is basically visual  we inherited it?  But this information for us, could be useful. That’s why we remember dreams.  We dream more under stress  related to difficulties. They are EMOTIONAL.

Applications and implications  Usually in mood disorders, there are alterations of sleep.  Babies have more REM sleep  this suggests that maybe one of the functions of brain activation is the developing of the brain itself.