Sleep & Dreams Flashcards
The role of brain in sleep
Explain Melatonin, SCN and Adenosine
Melatonin is known as a sleep hormone and is released by the pineal gland after the SCN signals it to when the sunlight decreases to make us tired. The SCN is an endogenous pacemaker in the brain whcih regulates the sleep-wake cylce.
Adenosine builds up throughout the day and increases the pressure to sleep. When we sleep, energy replaces the adenosine.
Circadian Rhythm
A timing mechanism which controls when we feel tired and alert. The hypothalamus controls the circadian rhythm, specifically the SCN whcih communicates with the pineal gland to release melatonin, a hormone that makes us feel sleepy.
Evidence
Siffre lived underground for two months, with no clock or sunlight. He had a sleep-wake cycle of 24 hours and 30 minutes which shows that circadian rhythms are innate.
The Stages of Sleep
Stage 1 is the lightest stage, the stage in which you feel like you are drifting off.
Stage 2 is when your body temperature decreases and heart rate slow down. Sleep spindles help to block external stimuli from waking you up.
Stages 3 and 4 are the deepest stages of sleep. You are very unresponsive to the external environment. If you are woken up now, you will feel groggy.
REM Sleep occurs when we are dreaming. We are paralysed in order for us not to act our dreams out. Thisis known as atonia.
Restoration Theory
Oswald
Theorises that NREM restores the body and REM restores the brain.
Whilst sleeping, the body repairs cells and tissues, it also gets rid of waste products and restores neurotransmitters.
Evidence
Shapiro et al found that after runners have ran an ultra-marathon, they sleep 90 minutes more than they normally do for the next two nights. This means that their body is taking more time to restore itself as the runners have damage to their body.
Dement & Kleitman Study
A study into REM Sleep and Dreaming
Aim
To investigate the relationship between dreaming and sleep stages.
To investigate whether eye movements during REM were connected to dream content.
To investigate whether there is an objective way to measure dreaming.
Method
A laboratory experiment using 9 participants, 7 male and 2 female. The participants were told not to consume any caffeine or alcohol before the experiment. An EEG was used to measure brain activity and an EOG was used to measure direction of eye movement. Participants were woken up by a doorbell and asked if they had been dreaming, what the content was and how long the dream was
Results
They found that 80% of the time that participants were woken up during REM, they were dreaming compared to the 9% of NREM.
Conclusion
Dream content is connected to eye movement
Dreaming occurs often during REM
The dreamer can accurately judge how long the dream is
Evaluate Dement & Kleitman
A strength is that it was a laboratory experiment with a high control of variables. This is a strength as the study could be replicated through other studies and get similar results.
A strength is that participants avoided caffeine and alcohol before the study. This is a strength as the external factors were controlled to make sure the results are reliable.
A weakness is that it used a low sample number. There were only 9 participants, 7 male, 2 female. This is a weakness as it doesn’t show the population as a whole and therefore results cannot be generalised to the population.
A weakness is that it was carried out in an artificial setting which lacks ecological validity. This is a weakness as it doesn’t show what a real night sleep looks like and therefore the participants could’ve not slept as well.
Evaluate Restoration Theory
Oswald
A weakness is that cell repair has been shown to carry out 24 hours of a day. This is a weakness as it shows that cell repair is not confined to sleep periods.
A weakness is that during REM sleep, the brain is very active and therefore protein synthesis cannot take place. This is a weakness as this contradicts Oswald’s theory.
Information Processing
Suggests that the different stages of sleep benefit the different types of learning and memory.
Procedural memory is benefited from REM sleep
Our memory of facts and events are benefited from stage 2
Early NREM stages benefit motor memory
Emotional memory is benefited from REM sleep
Evidence
Zammit found that people with insomnia had lower scores on tasks involving memory, concentration and problem solving than the people who didn’t have insomnia.
Reorganisational Theory
Crick & Mitchison
During sleep, unwanted memories are discarded to free space in the brain.
Parasitic memories are the memories that are useless and harmful to us and therefore are discarded.
Adaptive memories are the useful memories that we gathered in the day which will be beneficial to us to remember.
Evidence
Crick & Mitchison supported their theory by studying the enchida and dolphin as they do not have REM sleep. They found that the reason these animals have a bigger brain for their body is because they do not get rid of parasitic memories.
Czeisler Study
Aim
To find out whether disturbances from night-working in the sleep-wake cycle could be reduced by bright light exposure.
Method
A laboratory experiment with 8 male participants aged 22-29. They were told not to have any medications, drugs, caffeine or alcohol before the experiment and were tested. The participants then went to “night shifts” and through the night they stayed awake whilst completing cognitive tasks and reporting on their alertness and mood throughout the night. The experimental group then went to their blacked out home in the daytime and went to bed but the control group just had the normal daylight.
Results
The experimental group slept on average 7.7 hours but the control group slept on average 5.7 hours which shows that the experimental group slept 2 hours more on average.
Conclusion
Night shift workers should work in bright, artificial lighting during the night and pitch darkness at night to help them sleep.
Evaluate the Czeisler Study
A strength is that ecological validity was high as the participants went home to sleep. This is a strength as this means that the results can be generalised to real life scenarios.
A strength is that variables such as caffeine intake was controlled. This is a strength as it will make the results more valid.
A weakness is that only 8 males were used which doesn’t represent the population as a whole. This is a weakness as therefore the results cannot be generalised to females.
A weakness is the experiment carried out had a very complex procedure. This is a weakness as this means that the experiment took a long time and was time consuming.
Psychodynamic Processes
Unconscious, conscious, id, superego, ego
The unconscious mind comes out in our dreams. It is the deepest mind and contains are unnacceptable desires. The id desires pleasure and does not understand consequences.
The conscious mind is the mind that we have access to all the time. It stores our memories and our thoughts. The ego is what we are aware of - it has all of our rational thoughts and seperates the id and superego.
The superego is half conscious, half unconscious. It makes us feel guilty if we don’t follow the rules and knows all about moral code and society expectations.
Manifest and Latent Content of Dreams
The manifest content of our dream is what we can see in our dream. It is what it comes off as.
The latent content of our dream is what the dream truly mean deep down. The underlying truth.
Evidence
Little Hans dreamt that a big giraffe stomped on a smaller giraffe. The manifest content of his dream was a big giraffe stomping on a smaller giraffe. The latent content of his dream was that he wanted to get rid of his father to be with his mother, Freud found.
Hans also dreamt of marrying his mother, the manifest content. Freud found that the dream meant that Hans had romantic feelings towards his mother, the latent content.
Defence Mechanisms in Dreams
A psychological strategy that the ego uses to protect someone from their hard thoughts.
One defence mechanism is displacement. This is where the dreamer is protected from the latent content of the dream by replacing it with a nicer idea.
Symbolism in dreams is when an object acts as a deeper meaning to hide the conflict inside the mind.
Impact of Drugs on Sleep
Alcohol, Caffeine and Anti-histamine
Alcohol acts as a depressant. Depressants help us fall asleep but it becomes a stimulant which reduces sleep quality.
Adenosine production is from caffeine and therefore drinking caffeine in the afternoon will stop sleep.
Anti-histamine medication causes us to feel drowsy as it is a wakefulness neurotransmitter.
Impact of Lights on Sleep
Sunlight affects the SCN which controls our inner body clocks, the circadian rhythm.
Scheduled bright lights can helps with the negative effcts of night shifts, as found in the Czeisler study.
Artificial lights stops the production of melatonin and therefore the person will not sleep well.
