AS Psych: Dement & Kleitman (sleep and dreaming)
Psychology Being Investigated
1. Sleep is a state of reduced conscious awareness and reduced movement; it occurs on a daily cycle. Dement & Kleitman investigate the various stages of sleep and how they relate to dreaming
2. Ultradian rhythms are biological cycles that repeat more often than daily (e.g. the occurrence of periods of dreaming every 90 minutes during sleep). D&K’s study contributes to the study of these patterns, focusing on the cyclical pattern of REM sleep that occurs multiple times at night, shedding light on how they play a critical role in structure and quality of sleep + in the dreaming process
3. Electroencephalographs (EEG) measure electrical activity in the brain (brain wave activity) by measuring frequency and amplitude of changes. The records show which stage of sleep is occurring.
4. Dreams are vivid, visual sequences of imagery that occur at regular intervals during sleep and is associated with eye movements
5. Rapid Eye Movement/REM sleep is a stage of sleep all other muscles in the body are paralyzed; the eyes move rapidly under the lids (associated with vivid dreams)
6. Non Rapid Eye Movement/nREM sleep are the other stages of sleep (1-4) where the eyes are still (a.k.a quiescent sleep)
Background
Aserinsky and Kleitman (1955)
– Explored relationship between sleep and dreaming
– Showed that participants woken from REM sleep more likely to report a vivid, visual dream than when woken in other stages
– Found a characteristic brain wave pattern during REM sleep similar to wakefulness
– Suggested that strikingly vivid reports of dreams that participants reported when woken from REM sleep indicate eye movement is likely related to dream content
Aim
1. To investigate if dream recall differs between REM and nREM (quiescent) stages of sleep
2. To investigate if there’s a positive correlation between estimates of dream duration and length of REM sleep
3. To investigate if eye-movement patterns relate to dream content
Method
Research Method: Lab experiment
Research Design: Repeated Measures
Sample
– 7 male, 2 female
– 5 studied in detail (6-17 nights, 50-77 awakenings)
– 4 remaining had minimal data collected (only to confirm the results of first 5P, 1-2 nights, 4-10 awakenings)
Procedure
– Participants (P) reported to University of Chicago’s laboratory just before normal bedtime
– Instructed to eat normally, but abstain from alcoholic/caffeine-containing beverages
– 2-3 electrodes placed on scalp/near the eyes
– EEG fed into experimenter’s room, wires gathered into a single cord from participants head (can move easily, decrease entanglement)
– P sleeps in quiet, dark room
– EEG run continuously throughout sleep period at paper speed of 3 or 6 min per sec (faster speed for detailed examination of brain waves)
– Woken by doorbell various times during the night (asked to describe dream if they had, returned to sleep without being told about EEG pattern or if eyes were moving)
Aim #1
– Doorbell placed near bed, sufficiently loud for immediate awakening in all level of sleep
– P spoke into recording device near bed after woken up during/after REM
– Instructed to state if they had been dreaming + describe content of dream
– When P done speaking, experimenter (E) usually enter room to briefly interview on some part, but no other communication (ensure E doesn’t influence P’s memories)
– Operationalization of dreaming: can relate a coherent, fairly detailed description of dream content
– Choice of REM/nREM waking differed:
1) Random number table (KC & PM)
2) Groups of 3 REM, 3 nREM (DN)
3) Told they’d be woken in REM but actually random (WD)
4) No specific order, E’s choice (IR)
Aim #2
– Initially, P woken after variety of REM durations
– Asked to estimate time they had been dreaming, but deemed too difficult thought quite accurate
– Later, P woken every 5-15 mins in REM sleep at random → asked to guess how long they had been dreaming (5 OR 15 mins)
– Longer REM periods also used → E count number of words of dream narrative (for all periods)
Aim #3
– Direction of eye movement detected using EEG electrode around eyes
– P woken after a single eye movement has lasted >1min → asked to report dream
– Eye Movement patterns:
1) Mainly vertical
2) Mainly horizontal
3) Both horizontal and vertial
4) Very little/no movement
– EEG records compared to 20 naive, awake P + 5 experimental P → asked to watch distant + close up activity
Results
Aim #1
– 152 dreams were recalled in REM compared to 11 in nREM
– There were slightly less no recalls following REM sleep in the first half of the night than the later half of the night for the group studied intensively
– There were more no dream recalls in the first half of the night than the second half for the entire sample
Aim #2
– P were more accurate at estimating 5mins compared to 15mins
– On 88% of trials the participants estimated 5mins correctly while on 78% of trials the participants estimated 15mins correctly
– Positive correlation between REM duration and words in recall
– DN kept underestimating 15mins as 5mins
Aim #3
1) Mainly vertical
– P reported standing at the bottom of a cliff operating a hoist and looking at climbers on the cliff
– P reported climbing up a ladder and looking up and down as he climbed
– P reported playing basketball and looking up at the hoop as they shot/looking down to pick it up
2) Mainly horizontal
– 2 people throwing tomatoes at each other
3) Little/no eye movement
– Driving car and staring at road ahead, approach an intersection, startled by sudden appearance of car speeding at him from the left
– Driving car and staring at road ahead, just before awakening, saw a man standing on left side of road and hailed him as drove past
4) Mix of horizontal and vertical
– Talking to a group of people
– Fighting with someone
– Looking for something
Conclusion
1. Dream duration can be judged with accuracy (in REM)
2. REM patterns relate to dream content; they tend to fit in with what the dreamer is looking at
3. Dreams are not instant events but are experienced in real time
Ethical Issues
Deception – participant WD was misled about stage of sleep he was woken in which may cause distress
Informed consent – WD did not fully know what he was signing up for (i.e. full procedure of the study)
Protection from Harm – P were awaked lots of times, interrupting and disrupting sleep / ultradian rhythms
Application to Daily Life
EEG can detect REM/nREM sleep, so it can:
– be useful to investigate sleep disorders
– help diagnose sleep disorders
– insight gained can aid intervention and treatment for such disorders