Brainwave activity can be measured by an EEG (electroencephalogram). This provides the summary of electrical activity in the brain
Electrical activity of the muscle is measured by an EMG (electromyogram)
Eye movement is recorded via an EOG (electro-oculogram)
Stages of Sleep
Stage 1+2 Brain wavesslow down, amplitude increases. This is verylight sleep.
Stage 3+4 Deeper sleep characterised bydelta waves. Difficult to wake someone up.
REM sleep- measured by EOG. Associated withdreaming.Fast brain pattern.
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Aims
To discover if there is a link between REM sleep and dreaming.
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Procedure, Method and Sample
Nine adults, 7 males, 2 females. 5 studiede intensively.
Experimental sessions were repeated many times.
The pps reported to the sleep lab just before their usual bedtime. They had been told to eat normally but abstain from alcohol and caffine.
Electrodes were attached around the pps eyes (EOG) and scalp (EEG). The participant then went to sleep in a quiet darkened room.
At various time during the night pps were woken by a bell placed by their beds, These were done during REM or varying time periods after REM had stopped. On average they were woken 5.7 times a night.
Used different patterns for the 5 pps to avoid unintentional pattter. With 2 pps they used a table of random numbers. 1 pp was awoken during 3 REM periods and then 3 NREM periods. One was told he would be awoken during REM, but was actually awoken randomly.
None of the pps were told whether they had been having REM activity.
Ths pps were instructed to speak into a recording machine near their bed stating a) whether they had been dreaming b) describing the content of the dream and c) whether they were dreaming for 5 or 15 minutes.
An investigator was listening outside the room and occasionally entered the room to further question the participant.
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Lab Experiment
This is a lab experiment because it takes place in laboratory conditions - where extranoeous variables were controlled.
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Dependent Variables
The occurence of REM activity
Eye movement periods and accuracy of dream recall
Length of REM periods and subjective dream duration
Eye movement patterns and visual imagery of the dream
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Independent Variables
Whether the participant was awoken during REM or NREM sleep.
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Results
All pps had REM every night and was accompanied with a fast EEG patterns
Where REM activity was absent there were periods of deeper sleep
No REM activity occured during the initial onset of sleep
REM periods lasted between 3 and 50 minutes, with a mean of 20 minutes. The REM tended to be longer the later in the night it occured.
REM occured at fairly regular intervals. The average was an REM episode every 92 minutes.
If a pp was awoken during an REM period during the final hours of sleep, they often went back into REM sleep.
For all pps there was a high incidence of recall of dreams during REM periods and a low incidence of recall during NREM regardless of pattern
There were times when REM activity was not associated with a coherent dream and times when NREM did produce coherent dream recall.
Some participants were better at recalling their dreams
Most of the instances when dreams couldn't be recalled during REM occured in the early hours of the night
The overwhelming majority of pps were accurate in estimating the length of their dream in relation to REM activity
There appeared to be a positive link beween the type of eye movement and the content of the dream. One mainly horizontal dream recalled two people throwing tomatoes at each other. One mainly vertical dream recalled climbing ladders.
Participant did not recall more dreams as the study went on, so they did not become 'practiced'
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Conclusions
Dreaming is accompanied by REM activity.
It cannot be stated with complete certainty that dreaming cannot occur at other times
An objective measurement of dreaming may be accomplished by recording REMs during sleep.
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