Role of the Brain & Circadian Rhythms
The length of a Circadian Rhythm?
24 Hours
Name an environmental Factor?
Light
What does an EEG record?
Brain Electrical Activity
Purpose of REM sleep?
People need REM sleep to restore the brain processes that have depleted during the day
Aim? (2 marks)
To establish a link between:
REM sleep & dreaming.
dream content & direction of eye movement.
duration of a dream and someone’s perception of the length of the dream.
What does "Circadian" translate to?
circa = about, diem = a day
Stimulant
How long does REM sleep usually last for?
90 Minutes
N-REM sleep to repair the body and biological processes that have depleted during the day.
Method? (2 marks)
The method = lab experiment using PSG
9 adults - (7M, 2F)
Participants (Ps) asked to avoid caffeine or alcohol on the day of the study
An EEG to record brain activity
An EOG to record eye movement
Ps were awakened at various times to test:
dream recall
content of dream
duration of dream
What is the name of the French Scientist who spent 2 months in a cave?
Michel Siffre
How does alcohol impact sleep?
Alcohol initially acts as a depressant which can help people feel more sleepy and fall asleep quicker
Then it becomes a stimulant which reduces the quality of sleep as it changes the proportions of REM and n-REM sleep.
People typically go through how many cycles of sleep a night?
5
If lacking REM?
Harder to learn new things
May have more negative moods as neurotransmitters are not replenished
Results? (3 marks)
More dreams reported in REM than n-REM sleep.
Was association between patterns of REM & content of dream reports.
Eye movements appeared to link to what participants had been dreaming about
The results also tell us that REM:
Occurs later in the sleep cycle, in stage 5
Increase in length as the night progresses
Occurs at regular intervals during the night
Mainly associated with dreaming
Circadian clock checks its accuracy against what external factors?
E ______________ Z____________
Exogenous (External) Zeitgebers
How does antihistamines interfere with sleep patterns?
Histamine is a wakefulness neurotransmitter and as such, drowsiness is a major side effect of some anti-histamine medication.
Which stage is associated with sleepwalking, sleep talking and night terrors?
Stage 4
If lacking REM AND n-REM?
More difficult to concentrate and remember things
Conclusions? (2 marks)
Dreaming is reported in REM but not in nREM.
Ps can judge the length of their dream duration
Dreams progress in ‘real time’
Eye movement patterns relate to dream content.
What is the name of our Endogenous Pacemaker?
Suprachiasmatic Nucleus (SCN)
Amphetatime stimulates the CNS by activating receptors in the brain and increasing the activity of what?
Certain neurotransmitters including norepinephrine and dopamine (dopamine is associated with pleasure, movement and attention)
What is the state called when hallucinations may occur, eg, the feeling of falling
Hypnagogic State
What did Horne and Harley (1988) propose and find?
Believed that it was warming of the brain during exercise that led to increased sleep in Shapiro’s (1981) study.
To test this they heated people’s faces and heads with hairdryer.
Majority of the participants did indeed then go on to have longer period of n-REM sleep.
Their findings go against the idea that sleep repairs the body.
Evaluation? (4 marks)
Strength:
A lab experiment using a PSG was used:
so reliable results as cause & effect can easily be established.
High control over extraneous variables:
such as caffeine and alcohol consumption to avoid these factors affecting sleep
Weakness:
Was conducted in an artificial/controlled environment
therefore lacked ecological validity.
It was a small sample
therefore unable to generalise to the wider population.