Sleep and dreams Flashcards
(28 cards)
What is the circadian rhythm controlled by?
hypothalamus
What is the hypothalamus in charge of?
Keeping our bodies in a state of homeostasis
What part of the hypothalamus controls the sleep wake cycle?
The suprachiasmatic nucleus
Stage 1-2 of sleep
NREM - Stages 1 and 2 are light sleep stages. During these stages brainwave patterns become slower and more
rhythmic, starting with alpha waves progress to theta waves.
Stage 3-4 of sleep
NREM - Stages 3 and 4 are deep sleep or slow-wave sleep stages, where it is difficult to wake someone up. This
stage is associated with slower delta waves.
Stage 5 of sleep
REM - Stage 5 is REM (or dream) sleep. Here is the body is paralysed (to stop the person acting out their dream) and brain activity resembles that of an awake person.
Oswalds restoration theory
There are many different theories as to why we sleep. The biological process considers the restoration
theory as the most valid. Oswald (1966) believes that we sleep so that we can allow our body to heal itself
and repair any damage which it has sustained during the day.
He said that N-Rem sleep is needed for restoring the body such as allowing for new tissue growth,
repairing any muscle damage and removing waste chemicals whilst REM sleep is for replenishing
neurotransmitters which keep us alert.
Evidence for restoration theory
Shapiro et al (1981) – Researchers studied ultramarathon runners and found that they slept for an average of 90 minutes longer 2 days after running the ultramarathon, spending more time in N-Rem sleep
than before. This could be explained by their bodies need to repair more damage than if they did not run
an ultramarathon.
Evidence against restoration theory
Lavie et al (1984) – 20-year-old got hit with shrapnel which then prevented him from entering REM sleep.
However, this did not impact his cognition (as would be presumed because of his neurotransmitters not
being replenished) and he went on to study law with no issues.
Explain sleep to facilitate information processing
It is suggested that the different stages of sleep benefit different types of learning and memory:
Non-REM sleep benefits declarative memory (facts and events)
REM sleep is thought to particularly benefit procedural memory
REM sleep is important for emotional memory, and creativity and insight
Summary of cziesler et al
The study aimed to find a routine, including light exposure, which would help night shift workers fully adapt to daytime sleeping.
Eight healthy men in their 20s. None of whom regularly worked night-shift. Night Shift work was simulated in a laboratory setting at night.
There were two conditions - for night shift working; a control condition with low-level lighting and an experimental condition with high-level lighting.
In the control condition, the men were asked to use their home setting for any daytime sleeping they required. For this, sleeping was left unregulated and naturalistic.
Biological measures such as body temperature showed that the experimental group had had their circadian rhythms adjusted forward by 9 hours, while the control group stayed roughly the same.
Therefore the men’s daytime sleeping pattern more successfully adapted to a daytime circadian rhythm.
The conclusion of this experiment was that usual circadian maladjustment to night shift work can be treated and reversed with exposure to light at night and dark during the day.
The human circadian pacemaker can, within just three to four days, be shifted by up to twelve hours by properly timed exposure to bright light.
This light-dark intervention can significantly shift the associated decline in alertness, performance and quality of daytime sleeping, in favour of better night shift working.
Describe the reorganisational theory
The Reorganisational Theory, also known as the Crick and Mitchison theory (1983), suggests that the main function of REM sleep is to allow the brain to reorganise and process information gathered during the day. The brain uses sleep—especially REM sleep—to:
Strengthen useful memories and learning (adaptive information)
Forget or filter out unnecessary information (non-adaptive memories)
Prevent the brain from becoming overloaded with irrelevant data
This process is often referred to as “reverse learning”, where the brain actively unlearns information that could interfere with clear thinking and effective memory.
Summary of dement and kleitmens rem sleep study
Dement and Kleitman aimed to investigate the link between REM sleep and dreaming.
They used a lab experiment with participants who slept overnight in a sleep lab. Their brain activity and eye movements were monitored using EEGs (electroencephalograms).
Participants were woken at various times during REM and non-REM sleep and asked whether they had been dreaming.
Findings:
People were more likely to report dreams if woken during REM sleep (around 80% of the time) compared to non-REM sleep (around 9%).
The direction and length of eye movements were related to the content and length of dreams.
This showed a strong link between REM sleep and dreaming, and suggested that REM may play a key role in the dreaming process.
Links to dement and kleitman
This study links to the biological approach, especially within the Sleep and Dreams topic.
It supports the idea that dreaming has a physiological basis, and that REM sleep is an important biological stage associated with mental activity, particularly dream content and vividness.
Implications of dement and kleitmans study
Helped develop sleep science and opened the door to further studies on REM sleep and dreaming.
Provided empirical evidence that changed how psychologists understood the nature of dreams — moving from purely psychoanalytic (Freud) views to biological explanations.
Led to the development of sleep medicine and technology like polysomnography, used in sleep clinics today.
Influences theories of memory consolidation, as REM is now believed to play a role in processing emotional and cognitive information.
Comparisons to dement and kleitmens study
Crick & Mitchison’s Reorganisational Theory – both focus on REM sleep and its cognitive function, but Dement & Kleitman showed REM is associated with dreaming, while Crick & Mitchison argue it’s about forgetting information.
Oswald’s Restoration Theory – focuses more on SWS (slow-wave sleep) and physical recovery, whereas Dement & Kleitman focus on mental activity in REM.
Evaluation of dement and kleitmans study
Strengths:
Objective measurements using EEG machines increased scientific credibility.
Controlled lab setting meant high internal validity.
First study to give clear biological evidence of a link between REM and dreaming.
Limitations:
Low ecological validity – artificial lab setting may have affected natural sleep patterns.
Small sample size (9 participants) and mostly male, limiting generalisability.
Self-report data (on dreams) may be unreliable or inaccurate, due to memory distortion after waking.
evaluation of cziesler et als study
Strengths - The time difference between the mean low points of body temperature of the control versus the experimental group was huge, and statistically unlikely to have occurred by chance.
The light-dark treatment was implemented in an ecologically valid setting - the men’s homes. It also had a high degree of lab control for its night shift measurements.
Weaknesses - Small sample size.
Gender biased, making it hard to generalise the results.
The night shift work was simulated in a lab which may not have reflected typical working conditions. The work involved sitting in a chair for the duration of the night. This may lack ecological validity for some types of night shift work.
What is freuds psychodynamic approach to sleep and dreams
Sigmund Freud’s psychodynamic theory emphasizes the role of the unconscious mind in shaping human thoughts, emotions, and behaviors. Within this framework, Freud viewed dreams as a crucial window into the unconscious, proposing that they serve as a form of psychological release and expression for desires and conflicts that are typically repressed in waking life.
According to Freud, dreams are a manifestation of unconscious wish fulfillment. He argued that the mind is composed of three parts: the id (instinctual desires), the ego (rational self), and the superego (moral conscience). During waking hours, the ego and superego work to suppress the socially unacceptable impulses of the id. However, during sleep—particularly in REM sleep, when dreaming is most vivid—these defenses are weakened, allowing repressed thoughts and desires to emerge in disguised forms.
Freud distinguished between two levels of dream content:
Manifest Content: The actual events, images, and narrative of the dream as recalled by the dreamer. This content is often strange or nonsensical.
Latent Content: The hidden psychological meaning of the dream, representing unconscious wishes, fears, or unresolved conflicts.
Describe freuds defense mechanisms
- Repression
Definition: Forcing distressing memories, thoughts, or desires into the unconscious mind so they are not consciously remembered.
Example: A person who experienced a traumatic event in childhood may have no memory of it but still be affected by it unconsciously.
- Denial
Definition: Refusing to accept reality or facts because they are too uncomfortable to deal with.
Example: Someone who has been diagnosed with a serious illness might refuse to accept the diagnosis and act as if nothing is wrong.
- Displacement
Definition: Redirecting emotions from the original source to a safer or more acceptable target.
Example: A person angry at their boss might come home and take it out on their partner or pet.
- Projection
Definition: Attributing one’s own unacceptable thoughts or feelings to someone else.
Example: Someone who is cheating on a partner might accuse the partner of being unfaithful.
- Rationalization
Definition: Creating logical or socially acceptable explanations for behaviors or feelings that are actually driven by unconscious impulses.
Example: A student who fails an exam might say, “That test was unfair,” instead of admitting they didn’t study enough.
- Reaction Formation
Definition: Behaving in a way that is opposite to one’s true feelings, often because those feelings are socially unacceptable.
Example: A person who is unconsciously angry with someone might be overly friendly to them.
- Sublimation
Definition: Redirecting unacceptable impulses into socially acceptable or productive activities.
Example: Someone with aggressive urges might channel that energy into sports or physical training.
- Regression
Definition: Reverting to behaviors characteristic of an earlier stage of development.
Example: A stressed adult might start acting childishly—throwing a tantrum or seeking comfort items like food or toys.
- Identification
Definition: Adopting the characteristics or behaviors of someone else, often to deal with feelings of inferiority or fear.
Example: A child who feels powerless may imitate a strong, authoritative parent or superhero.
Analyse factors affecting sleep.
- caffeine is a type of drug which acts as a stimulant which implies that the
intake of too much caffeine will disrupt the sleep/wake cycle (1) - research studies have found that caffeine can delay the timing of the body
clock, which in turn will reduce the total sleep time and its quality (1)
however, this also depends on the amount, the timing and concentration of
caffeine consumed (1) - one application of these findings has been to ban energy drinks that are high in
concentration of caffeine to under-16s in Scotland (1) - there are individual differences in how caffeine affects sleep as some people
have a higher tolerance and sleep would therefore be less affected (1) - scheduled bright light exposure can treat the negative effects of shift work (1)
- light therapy is found to also alleviate symptoms of jet lag when travelling
through different time zones (1) - research into the effects of blue light on sleep has led to recommendations to
avoid the use of LED devices in the hour prior to sleep (1) - LED devices now use red light technology to replace the more harmful effects of
blue light. (1)
Comparison to restorational theory
Reorganisational theory – sleep not to grow and repair but to strengthen thoughts and
memories
Implications of restorational theory
More active species should sleep more – not always the case (sloths)
Memory problems if we don't sleep enough – not being able to concentrate in class
Growth hormones secreted during NREM sleep – this is why babies sleep more.
Induced commas – used to help brain recovery
Implications of Dement and Kleitman
These results could help in the creation of sleep disorder interventions.
