Module 8: Sleep and Dreaming Flashcards
Explain NREM sleep
- Stage 1: light sleep, easily woken, alpha/theta brainwaves, eye movements slow
- Stage 2: late night, brain activity bursts (spindles), body temperature drops, heart rate slows, eye movements stop
- Stage 3: transition between 2 and 4
- Stage 4: deep sleep, slow delta waves, hard to wake, sleepwalking/nightmares in children
Explain REM sleep
- Rapid eye movement
- Dreaming - 2hrs per night
- Sensory blockade
- Movement inhibition (spinal cord neurons turned off by pons)
- Heart rate/blood pressure rises
Explain the sleep cycle
- Five cycles (1 = 90mins)
- Deep sleep and little REM –> light sleep and long REM (up to an hour)
What are the functions and benefits of sleep?
- Deep sleep stops after age ~65
- Sleep needed for learning and survival
- 20% of sleep is REM, 50% for babies
- Dreaming can occur in NREM
- Adults need 7-8hrs, teens need 9hrs
Explain circadian rhythms
- Controlled by suprachiasmatic nuclei (SCN) which is set by external triggers
- 24 hour cycle (sleep/wake, body temperature)
Explain zeitgebers as an external influence on sleep
- Environmental cues (light/dark cycle, seasons, hunger)
- Entrainment - biological rhythms being matched to external triggers
What are the strengths and weaknesses of zeitgebers as an external influence on sleep?
- Strengths: Practical applications (aid shift workers), Mistlberger & Skene (2004) found light a strong influence on sleep
- Weaknesses: Differing findings (Siffre 1975), studies usually unnatural
Explain ultradian rhythms
- Less than 24 hours
- Sleep/REM cycle, heart rate, hunger, etc
Explain internal influences on sleep
- Biological clock internal, keeps all rhythms synchronised
- Hormones: adrenaline/cortisol affect sleep, sleep resets hormones
- Melatonin signals need to sleep, released by pineal gland (trigger by darkness)
- Melatonin works as medication for insomnia/jet-lag (not shift workers)
What are the strengths of internal influences on sleep?
- Evidence from animal studies
- Miles et al (1977) human study on blind person
- Li-You Chan et al. (2015) evidence for melatonin
What are the weaknesses of the theory of internal influences on sleep?
- Cannot always generalise animals studies to humans
- Evidence relating to blindness is weak
What are the symptoms of insomnia?
- Difficulty falling asleep
- Waking a lot in the night
- Not feeling refreshed waking up
- Feeling stressed/irritable
- Acute/chronic, 1 in 3 people, more common in older people
Give explanations for insomnia
- Jet lag/night shifts
- Health conditions (physical/mental)
- Medication, food, drink (hormones affected)
What are the symptoms of narcolepsy?
- No control over sleep/wake cycle
- EDS (excessive daytime sleepiness)
- Hallucinations and vivid dreams
- Cataplexy in 70% - loss of muscle power/tone due to onset of strong emotions (e.g laughter)
- Sleep paralysis and abnormal REM
- Affects 1 in 2000 people
Give explanations for narcolepsy
- Lack of hypocretin
- May be genetic
- Stress/trauma
- May have evolutionary benefit (play dead)
Explain Freud’s theory of dreaming
- We repress unconscious wishes/desires and dreams can uncover them (through dreamwork)
- Know them, they’re released from the subconscious, you no longer take up energy repressing them, no more anxiety
Explain dreamwork (of Freud’s theory of dreaming)
- How the mind protects itself by hiding unconscious desires in dreams:
- Condensation - many ideas appear as one
- Displacement - what seems important is not (shifting away focus)
- Secondary elaboration - added details to make sense of story
- Symbolic meanings different for everyone, knowledge of patient needed
What are the strengths of Freud’s theory of dreaming?
Qualitative, detailed, focused - strengthens validity
What are the weaknesses of Freud’s theory of dreaming?
Cannot be tested/shown as true or false - unscientific
Explain Hobson and McCarley’s (1997) Activation-Synthesis theory of dreaming
- Activation: neurons randomly activated –> messages (thoughts) sent in brain - all information internally generated
- Synthesis: brain makes sense of internal info the same way it does with external - this creates dreams
What are the strengths of Hobson and McCarley’s (1997) Activation-Synthesis theory of dreaming?
- Evidence: senses blocked so dreams must be internal, pons active during cats’ dreaming
- Model still being used/investigated today
What are the weaknesses of Hobson and McCarley’s (1997) Activation-Synthesis theory of dreaming?
- Animal studies not always generalisable
- Dreams often linked to previous days’ events (not entirely random)
- Has been built on/amended (didn’t last on its own merits)
What was the background of Freud’s (1909) Little Hans study?
- Psychosexual stages of development
- 3-5yrs old: phallic stage, gendered behaviour through identifying with same-sex parent, oedipus complex
What were the aims of Freud’s (1909) Little Hans study?
- Help the individual
- Gather evidence for theory on how children develop (psychosexual stages)
What was the procedure of Freud’s (1909) Little Hans study?
- Detailed information from Hans’ parents
- Dreams and phobia of horses (including but not limited to)
- Only some information from Little Hans himself
What were the results of Freud’s (1909) Little Hans study?
- Hans saw a horse fall in the street & had a fear of horses (black around mouth): horses = father (moustache), unconscious fear (oedipus complex), rearranged father to ‘grandfather’ role to alleviate anxiety
- Early dream, mother was gone: fear father would take mother away (oedipus complex)
- Dream, big & crumpled giraffe, takes small giraffe and big one shouts at him: mother and father, oedipus complex (Hans denied this)
What were the conclusions of Freud’s (1909) Little Hans study?
- Evidence for Oedipus complex (fear of father, wanting to posses mother)
- Fear of horses an example of this
What are the strengths of Freud’s (1909) Little Hans study?
- In-depth detailed qualitative analyses
- Carefully documented, reflective account, scientifically carried out
What are the weaknesses of Freud’s (1909) Little Hans study?
- Parents followers of Freud’s ideas, so information passed on was biased
- Case studies not generalisable and unsuited for building theories (as Freud was doing)
- Learning explanation for horse phobia - saw a horse fall and die
What was the background of Siffre (1973) 6 Months Alone in a Cave?
- Replicate previous 1962 study (also conducted by Michael Siffre, on himself and others - 24hr clock for him, 48hr for others)
- NASA sponsored the study
What were the aims of Siffre (1973) 6 Months Alone in a Cave?
- Investigate how astronauts would react to not having zeitgebers to set biological clock
- Find whether ‘natural’ sleep cycle 24hr or 48hr
What was the procedure of Siffre (1973) 6 Months Alone in a Cave?
- Spent 14 Feb 1972 - Sep 1972 alone in a cave in Texas
- No indication of date/time, woke up and turned lights on, was tired and turned lights off
- Memory/physical tests taken after waking up
What were the results of Siffre (1973) 6 Months Alone in a Cave?
- Became depressed/suicidal, desperate for companionship
- Short term memory negatively affected
- Sleep-wake cycle initially longer than 24hrs, but then ranged from 18-52hrs
What are the strengths of Siffre (1973) 6 Months Alone in a Cave?
- Significant quantitative and qualitative data
- Long period - 6 months, ensure no patterns could be found in the sleep-wake cycle
What were the conclusions of Siffre (1973) 6 Months Alone in a Cave?
- Body clock manageable, though erratic/variable without zeitgebers
- Companionship required
What are the weaknesses of Siffre (1973) 6 Months Alone in a Cave?
- Lights upon waking - external cue
- Case study, not generalisable (to astronauts)
