| concept | info | evaluation | |
| Stages of sleep
Sleep cycle – process by which people pass through 4 stages of sleep and REM sleep in succession several times during full sleep |
Stage 1 – sleep onset
– Restful brainwaves – theta waves – Easily woken Stage 2 – late night – Slower theta waves with bursts of activity – Slower brainwaves but with spindles of activity Stage 3 – deep sleep – Slow delta waves mixed with faster waves – Stage between light and deep sleep Stage 4 – deep sleep – All slow delta waves – Very hard to wake someone |
Benefits of sleep
– Helps humans maintain brain chemistry, by allowing neurons in brain time to repair themselves – Studies depriving rats of sleep found that they had a shortened life span of just 5 weeks, compared to normal 2-3 years – REM sleep o Helps stimulate regions responsible for learning and memory o which helps development of brain especially during infancy when babies have more REM sleep lack – problems coping in stressful situations, migraines and weight gain |
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| Internal and external influences on sleep
circadian rhythm aligns sleep and wakefulness with day and night to create stable cycle of restorative rest that enables increased daytime activity
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Circadian rhythm
– biological (internal), bodily rhythm that has daily (24hr) cycle – e.g., sleep-wake cycle, body temp and some hormonal changes – run ‘in the background’ to carry out essential functions and processes – closely connected to day and night – controlled by suprachiasmatic nucleus (SCN) o circadian pacemaker/’master clock’ in hypothalamus o at different times of day, clock genes in SCN send signals to regulate activity throughout body o highly sensitive to light – critical external cue influencing signals sent to co-ordinate internal clocks in body Sleep-wake cycles – during day – light exposure causes SCN to send signals that generate alertness and helps us keep awake – at night – SCN initiates production of melatonin and pineal gland (hormone that promotes sleep) and then keeps transmitting signals that help us stay asleep through night d i s r u p t i o n s to circadian rhythm – jet lag o person crossing multiple time zones in short period of time o until person’s circadian rhythm can acclimate to day-night cycle of new location, likely to suffer sleeping problems, fatigue or daytime irritability – shift work o requires having to work through night and sleep through day o puts person’s sleep schedule directly at odds with local daylight hours Ultradian rhythm – bodily rhythm occurring in period of less than 24hrs – e.g., sleep cycle (5 cycles of 90 minute periods), appetites, heart rate or levels of alertness |
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| – internal | Endogenous – internal pacemakers, factors influencing sleep-wake cycle
Hormones – chemicals secreted by glands into bloodstream Melatonin – produced by pineal gland – when levels increase, this signals need for sleep – production and release of melatonin triggered by darkness – melatonin tablets – often treatment for people with insomnia |
Strengths
– practical applications – melatonin tablets can be used as treatment for insomnia – research supporting o Miles et al (1977) found that a blind man’s bodily rhythm was 25hrs (close to normal 24hrs), suggesting that even without light, internal factors govern our circadian rhythm o Studies found that when hamsters have SCN removed, their sleep-wake pattern becomes random, suggesting SCN plays key role in setting biological clock o Research shows there is more ACTH (hormone affecting sleep and linked to feeling stressed) in people with insomnia than in people who sleep well
Weaknesses – Can’t fully explain sleep patterns – individuals able to override influence of internal factors through use of stimulant drugs like caffeine – Problems generalising findings o Animal studies – brains and bodies of humans and other animals may work very differently o Population validity – can’t generalise findings from blind people to wider population – not all forms are the same and some may still be able to perceive light
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| – external | Exogenous – external influences on sleep-wake cycle
Zeitgebers – ‘time-givers’ – exogenous cues Light – lets body know if it’s night or day – can influence sleep-wake cycle and release of melatonin other external factors include food, drink and drugs e.g., caffeine as stimulant drug |
Strengths
– practical applications – advising shift workers to darken bedroom at night time, due to understanding how zeitgebers like light affect sleep patterns – Research supporting o Siffre (1975) found that without light as external cue, sleep-wake cycle is not set around 24hr clock; instead, a cycle of sleep/wakefulness can stretch from 18-52 hrs Weaknesses – Not applicable to everyone – Inuits in arctic circle said to have similar sleep-pattern all-year round, despite spending approx., 6 months in complete darkness. Suggests endogenous influences may override external changes in lights |
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| Sleep disorders | Narcolepsy | Symptoms
– No control over sleep-wake cycle – Falling asleep suddenly at anytime – Excessive daytime sleepiness – Hallucinations – Cataplexy (loss of muscle power at any point) Explanation – Lack of hypocretin – which usually keeps us awake – Genetic influence – linked to variations in chromosome 6 |
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| Insomnia | Symptoms
– Difficulty falling and staying asleep – Not feeling refreshed on waking – Irritability and inability to concentrate Explanation – Lifestyle – jet lag or shift work – Mental and physical ill-health (e.g., depression or heart problems) – Side effects from medication (e.g., antidepressants) or food and drink, like alcohol or caffeine |
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| Activation synthesis theory | – Put forward by Hobson & McCarly
– Suggests dreams are caused by random activation of neurones – Triggering random impulses in pons (in brainstem), which are synthesised by cerebral cortex into stories – Dreams are random and have no meaning (essentially just internally-generated information) – Dreams occur during REM sleep, when brain is very active – Sensory blockade prevents information entering brain – Leading to muscle paralysis due to movement inhibition |
Strengths
– Research supporting § Research shows that in sleep labs, people experience increased brain activity during REM sleep, yet muscles are paralysed, and no sensory info is taken in. supports that dreams are result of brain trying to process random thoughts § Hobson and McCarley found that cats, during REM sleep had increased activity in the Pons – structure involved in shutting down physical movement and where random impulses are generated – Scientific methods – EEGs – used to record objective data on brainwaves during sleep, giving AST credibility Weaknesses – Rather than being random, many link their dreams to events experienced on previous day, suggests firing of neurons in brain during REM sleep has some meaning – Recurring dreams – evidence to suggest dreams could be linked to our unconscious or anxieties and worries rather than random surges of stimulation in brain – Lucid dreaming – suggests that dreams are not random if some people are able to control dreams – Freud argues dreams are an interpretable form of wish fulfilment, rather than random neuron activation – Can only explain formation of dream states, not purpose dreams have in brain processing and functionality |
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| Freud’s theory of dreaming | – Dreams have hidden symbols and meanings, which can reveal our unconscious (often repressed) thoughts and feelings that affect our behaviour, when analysed
– Manifest content – part which we can remember – Latent content – true, symbolic meaning of unconscious wish – Mind attempts to keep latent content hidden through: · Condensation – many ideas condensed into one to hide important aspects · Displacement – unimportant elements made to seem more important, to shift attention away from true meaning · Secondary elaboration – when extra things are added so it’ll make more sense, often hiding latent content |
Strengths
– Practical applications – offers unique way of studying unconscious mind through mental health treatment of ‘psychoanalysis’ – useful for analysing latent content – High in validity – detailed qualitative data gathered, providing greater insight Weaknesses – Low reliability – subjective theory as dreams may be interpreted by other researchers completely differently – Unfalsifiable – not easily tested as impossible to measure unconscious mind objectively – providing limited accuracy when explaining dream content |
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| K E Y S T U D I E S | |||
| Freud (1909)
Little Hans – case study |
– All children develop in series of psychosexual stages
– Oedipus complex – where young boy feels strong feeling of hatred towards father for ‘possessing’ their mother, wanting father out of way as rival while fearing castration • During phallic stage of development procedure – Gathering qualitative, detailed info from regular letters sent by parents about Little Hans – Studied dreams and phobias of horses – developed at age 5 – Through method of psychoanalysis – considering how issues may be symbols of hidden unconscious desired phobia of horses – Thought black bits around horses’ mouth – fathers’ moustache – Horse – symbol for Han’s father – Phobia – unconscious fear of his father, angry for him wanting his mother giraffe dream – Big giraffe shouted at Hans for taking crumpled giraffe away – Interpreted as Little Hans’ wanting to take mother away from father – Linked to how Little Hans liked getting into bed with parents in morning – something his father didn’t like |
strengths
– High validity – in-depth, detailed data gathered, qualitative nature weaknesses – Low generalisability – case about unique individual + sample size of one, not representative of target population (young boys in phallic stage) and lacking population validity • Wrong to generalise findings to wider population and claim all children go through same stages of development – Bias – little Hans’ parents knew about Freud’s theory (Oedipus complex), so could’ve sent over information that suited the complex C O N C L U S I O N S – Little Hans’ supports theory that children develop in series of psychosexual stages – Specifically supporting theory of Oedipus complex occurring during phallic stage of development |
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| Siffre (1975) | aim – to investigate effects of living underground in a cave without external cues on the 24hr sleep-wake cycle
tests – Blood pressure – Mental agility – Physical agility (firing pellet rifle for co-ordination, cycling 3 miles) – Memory health deterioration – Memory becoming poor – Confusing thoughts – Emotions + panic – Low mood – Poor agility sleep-wake cycle varying from 18 – 51hrs most common – 48 hrs sleep wake cycle in 2 different extended periods of time |
strengths
– High validity · Lots of data collected about physical and mental functioning, produced detailed record or progress or lack of · Spent 6 months in cave – if any less time, may have found particular rhythm by chance weaknesses – Low validity – strong lights turnt on/off when asleep/awake, could’ve affected internal body clock – acting as cues – One-off case study – siffre’s situation was unique (e.g., dealing with dampness and noise of mice) – difficult to generalise findings to every person finding themselves without external cues, e.g., light |
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