Sleep+dreams biatch Flashcards
:ppp
Stage 1 sleep
- 5-10 minutes
- don’t know you were sleeping if woken
- alpha waves produced
Stage 2 sleep
-10-20 mins
- sleep spindles produced
- theta waves produced
- decreased body temperature
- decreased heart rate
stage 3 sleep
- 30+ min
- deep sleep
- slow wave sleep
- hard to wake
- delta waves
stage 4 sleep
- lasts for ~30min
-deep sleep - when bed wetting/sleep walking occurs
stage 5 sleep
- REM sleep
- body is paralysed
- when dreams occur
- ~90min into sleep
biological explanation of dreams
- meaningless side effect of brain activity during sleep
activation-synthesis hypothesis (Allan Hobson and Robert McCarley (1977)) describe and evaluate
- dreams are caused by random neurons firing in the Pons (activation)
- messages from these neurons are sent to the neocortex, which tries to make sense of them (synthesis) and creates a narrative (dreams)
Evaluation: - Supported by brain scans
- Doesn’t explain dreams about specific events/people/things
- Many people do not agree that dreams are completely random
Circadian rhythms are controlled by:
- Endogenous pacemaker (SCN Suprachiasmatic nucleus)
-Exogenous zeitgeibers (light, social cues)
How does the SCN work?
- receives light/dark from the eyes
- makes the pineal gland produce melatonin
- melatonin is released gradually, reaches its peak at midnight and is reduced towards the morning
Siffre Cave Study (1962)
- lived in a cave for 2 months
- had no natural light
- maintained a circadian rhythm of just over 24 hours
Factors affecting sleep (6)
- Stimulants
- Amphetamines
- Alcohol
- Light
- Shift work
- Travel
How do stimulants affect sleep?
Caffeine~~~
- effective in 15 minutes
- half-life of 5 hours
- blocks adenosine receptors
- reduces melatonin production
- increases adrenaline production (heart rate, breathing rate, etc)
How do amphetamines affect sleep?
Speed, Adderall, Ritalin~~~
- cause increased wakefulness
How does alcohol affect sleep
- depressant, aids in falling asleep
- stimulant, reduces sleep quality
- changes proportions of REM and nREM sleep
How does light affect sleep? (mention findings of 3 studies)
- Santhi et al (2012) blue light affects melatonin levels more than normal artificial light
- Chang et al (2015) people using tablets/ereaders emitting blue light before bed took longer to get to sleep, produced less melatonin, had less REM and were less alert in the morning
- Czeisler, bright light and complete darkness could completely change circadian rhythm
How can travel affect sleep?
- Jet lag
- When the circadian rhythm needs to adjust to a new timezone
Czeisler et al (1990) Aim:
Aim: To find out if disturbances in the sleep/wake cycle created by working at night could be treated by a programme of bright light at night and complete darkness during the day
Czeisler et al (1990) Hypothesis
Hypothesis: Exposing night workers to bright light at night and complete darkness during the day will prevent disturbances to the sleep/wake cycle
Czeisler et al (1990) Participants
Participants: 8 healthy men (22-29) who did not usually work at night
Czeisler et al (1990) Control/experimental condition
Control:
- Participants worked at night in normal artificial lighting
Experimental:
- Worked in extremely bright light at night and had almost complete darkness during the day
- Worked from 11:45 for 6 days
- They measured cognitive function, alertness, blood plasma cortisol level, urinary excretion rate and BBT
Czeisler et al (1990) Results
- mean temp of control fell at night like normal
- mean temp of experimental group fell at midday after 4 days of treatment
- circadian adaption included urinary excretion rate, concentration, alertness and cognitive performance
- treatment group adapted their circadian rhythm while the control group did not
Czeisler et al (1990) Conclusion
Disturbances in the sleep/wake cycle (for example cognitive performance and quality of daytime sleep) can be treated effectively by bright light at night and darkness during the day
Czeisler et al (1990) Evaluation
Strengths: - led to design of light treatments for night workers and travelers
- variables such as caffeine and alcohol intake were controlled for, increasing the validity
Weaknesses: - temp and blood taken constantly, could have affected participants negatively
- complex, time consuming procedures
- only 8 males
Distortion of true dream meaning:
- Condensation: multiple symbols get mixed up together
- Secondary Elaboration: Dreamer’s own interpretation of the dream after waking, can involve bits added in afterwards
Defence Mechanisms in dreams:
- Secondary elaboration
- Repression
- Displacement
Defence mechanism secondary elaboration
- Hiding embarrassing parts when retelling the dream
Defence mechanism Repression
- Id’s desires are translated into hidden symbols but are repressed during the day
Strengths of the psychoanalytic approach:
- Very influential for everyday language and culture
- before Freud, people thought that dreams were a prediction of the future so his ideas were better than previous
- Solms (1999) found that stroke patients couldn’t dream when the part of the brain governing desires was damaged
Weaknesses of the psychoanalytic approach:
- Relies too heavily on case studies
- Jung (also a psychoanalyst) thought that the symbols in dreams were unique to the individual and not generalised
- Wish fulfilment doesn’t explain nightmares
- Lack of scientific evidence
The cognitive approach to sleep and dreams:
- Explains behaviour in terms of beliefs and schemas
- Dreams are a by-product of memories being reorganised and they have no deeper meaning
- Dream content depends on the importance of the memory being re organised and what has been recently learned by the individual
Crick and Mitchison’s (1986) reorganisational (cognitive) theory of sleep: Function of dreams:
- To make the most of the brain’s ability to store memories
Crick and Mitchison’s (1986) reorganisational (cognitive) theory of sleep: Reverse learning concept
- The neocortex is overloaded with information during the day
- Dreams are a side effect of reverse learning or decluttering parasitic memories
- The random memories activated cause dreams
Crick and Mitchison’s (1986) reorganisational (cognitive) theory of sleep: 2 kinds of memories
- Adaptive: useful memories
- Parasitic: useless/harmful memories, lead to obsessions and compulsive behaviour
Crick and Mitchison’s (1986) reorganisational (cognitive) theory of sleep: Evidence for
- Dolphins have larger brains in proportion to body size and do not REM sleep, more space for parasitic memories
- Neural network computer programmes create an unlearning system
Crick and Mitchison’s (1986) reorganisational (cognitive) theory of sleep: Evidence against
- Walker et al (2003) A finger tapping task proved that memories are more reliably coded after sleep
- Mednick et al (2003) A perception task was completed better after a 90 minute nap, sleep helps to strengthen memories
- Seehagen et al (2015) Babies could recall new actions better after having nap
- MAOIs for treating depression reduce REM sleep, but those taking them experience an improvement in memory function not memory dysfunction
Crick and Mitchison’s (1986) reorganisational (cognitive) theory of sleep: Evaluation
Weaknesses:
- Based on computer models and research into dolphins, lacks research on humans
- Does not explain why dreams have a narrative
Crick and Mitchison’s (1986) reorganisational (cognitive) theory of sleep: Application
- students should get a good night’s sleep to perform their best in school
Ostwald’s (1966) Restoration theory of sleep
- Sleep restores a worn-out body and replenishes vital neurotransmitters
- REM sleep is for brain repair and nREM is for body repair
Repairs: *Minor injuries such as to skin or muscles
*Removes waste chemical build up in muscles
*Replenishes neurotransmitters or energy in the brain - The period of inactivity happening during sleep is vital for restoration as no new damage is happening to the body
Ostwald’s (1966) Restoration theory of sleep: Evidence for (Peter Tripp (1959))
- Wakeathon- 8 days (200hrs) no sleep
- experienced hullucinations and delusions whilst awake and seemed to suffer longer term effects
- stayed awake for 201hrs, slept for 13-22
- Study did not take place in a lab and had a sample size of 1
Ostwald’s (1966) Restoration theory of sleep: Evidence for (Randy Gardner (1963))
- 17yrs old
- 11 days no sleep
- Speech and vision problems
- recovered much better than Peter Tripp
- caught up on 25% of sleep debt (15 hours) after
- spent much longer in REM sleep afterwards
Ostwald’s (1966) Restoration theory of sleep: Evidence for (Shapiro et al (1981)
- Compared sleep of marathon runners with non marathon runners
- Running long distances reduced REM and increased SWS in the 2 days after a marathon
Ostwald’s (1966) Restoration theory of sleep: Evidence for (Spinal operations/drug overdoses)
- Those who had spinal operations or drug overdoses spent longer in REM sleep afterwards, suggesting that this stage is necessary for brain/nervous system repair
Ostwald’s (1966) Restoration theory of sleep: Evidence for (Neurotransmitter levels)
- Neurotransmitter levels deplete throughout the day
- suggesting that they need to be replenished at night
Ostwald’s (1966) Restoration theory of sleep: Evidence for: (Northwestern University (2010))
- Elderly insomniacs spent longer asleep after daily aerobic exercise
- they had to repair their bodies
Ostwald’s (1966) Restoration theory of sleep: Evidence for: (Rat study (1983))
- Rats kept awake on a rotating platform with food and water
- Rats died after 3 weeks no sleep suggesting that sleep is essential somehow
Ostwald’s (1966) Restoration theory of sleep: Evidence for: (Car crash study (2018))
- Sleeping too little results in poorer performance and an increased chance of accidents
Ostwald’s (1966) Restoration theory of sleep: Evidence against: (Horne (1978))
- Sleep depivation did not interfere with participants’ ability to ply sports or make them ill, sleep is not essential for physical functioning in the long run
Dement and Kleitman (1957) REM Sleep Study
Aim:
- To find out if there was a link between REM sleep and dreaming
Dement and Kleitman (1957) REM Sleep Study
Hypotheses:
- There would be a relationship between REM sleep and reports of dreaming
- The dream itself would be linked to dream content
- The duration of eye movement would match up with reported dream duration
Dement and Kleitman (1957) REM Sleep Study
Participants:-
- 9
- 2 females, 7 males
- Kleitman took part
- avoided caffeine and alcohol
Dement and Kleitman (1957) REM Sleep Study
Method:
- Observed sleeping over a number of nights
- Repeatedly woken during sleep
- EEG measurements recorded eye movement and brain activity
- Asked to report if they had been dreaming, the content of the dream, and for how long they had been dreaming
Dement and Kleitman (1957) REM Sleep Study
Results:
- Participants were more likely to say they had been dreaming in REM sleep (80%) than nREM sleep (9%)
- Patterns of eye movement showed a link with the type of dream recalled
- Duration of REM showed a link with dream duration
Dement and Kleitman (1957) REM Sleep Study
Conclusions:
- Dreams can be objectively measured
- REM is the stage of sleep where most dreaming occurs
- the pattern of eye movement in REM reflects what the dream is about
- We can judge dream length accurately
Dement and Kleitman (1957) REM Sleep Study
Evaluation:
- Highly controlled in a lab setting, high validity
- Clear, well defined methodology helped with replication and therefore reliability
- objectively measured dreams, no unscientific psychoanalysis involved
- enabled researchers to determine the purpose of REM sleep
- Small sample size reduces reliability and makes generalisation harder
- relationship between REM sleep and dreaming was not found in all cases
- Lab setting lacks ecological validity and mundane realism
- Can’t be generalised to children.
