Biological Rhythms

AQA psychology - unit one, biological rhythms

HideShow resource information
  • Created by: megan
  • Created on: 17-01-12 10:25

Circadian Rhythms

Circadian Rhythm - 24hrs e.g. SLEEP-WAKE CYCLE

Endogenous pacemaker - internal biological clocks

exogenous zeitgebers - external cues (e.g light, noise, food)

SLEEP WAKE CYCLE

  • michael siffre ( in cave) - cycle settled to just over 24hr. case study.
  • Folkard - speeding of clock - cycle remained at 24hrs, not 22hrs
  • use of lighting? dim light's??
  • individual differences - cycles of 13 - 65hrs
  • morning / night people ( larks and owls)
  • chronotheraputics - timing of medication
1 of 16

Circadian Rhythms (2)

CORE BODY TEMP

  • lowest at 4.30am, highest at 6.00pm. dip/trough at 1.00pm (bi-daily rhythm)
  • cognative abilities - Folkard (story recall) , Gupta (IQ)
  • suggestion- ^ temp = ^ arousal = ^ cognative ability
  • school starting time dispute

HORMONES

  • Cortisol levels peak at 6.00am - alertness
  • melatonin levels peak at 12.00 am - sleepiness

BIOLOGICAL APPROACH

  • Determinism
  • can overide to a point, but not completely
  • blind boy - internal clock ahead - use of stimulants and sedatives
2 of 16

ultradian

Ultradian rhythm - less than a day (sleep cycle)

SLEEP CYCLE

  • SWS - stages 1&2 (light sleep) Stages 3&4 ( deep sleep, production of GH)
  • cycle lasts 90 minutes
  • REM - dreaming - dement & kleitman. waking during REM, most dreaming

BRAIN REST-ACTIVITY CYCLE

  • 90 minute cycle inside sleep-wake cycle
  • Freidman and Fisher - eating/drinking. psych patients > ethical issues
  • forms timing for biological processes to work in unison
3 of 16

Infradian

infradian - more than a day, less than a year (menstrual cycle)

MONTHLY CYCLES

  • menstural cycle - Russel et al - syncronisation (sweat on lip) phenomones
  • PSM - Symptoms may lad to crimes. Ms English - murder of husband
  • temperature cycle in men is apparent (22 days)

Seasonal affective disorder (SAD)

  • depression in winter
  • darkness - increased levels of melatonin and seratonin
  • phototherapy (light box) - very effective, more than placebo light box
4 of 16

Endogenous Pacemakers

Endogenous pacemakers - internal rhythms

THE SCN

  • obtains light information from the optic nerve
  • ventral SCN - quickly reset by external cues
  • dorsal SCN - less effected by external cues 
  • mutant SCN transplanted into hamster - mutation of internal rhythm
  • chipmunk - removal of SCN - killed by predators (awake when awake)
  • desynchronisation - symptoms as of jet lag

THE PINEAL GLAND AND MELATONIN

  • SCN > signals to pineal gland > ^ production of melatonin at night
  • regulated by light - production inhibited in light
5 of 16

exongenous zeitgebers

Exogenous zeitgebers - external cues

LIGHT

  • can reset SCN and protein clock (light sensative)
  • cambell & murphy - light on knees - protein clock
  • industrial societies/ well lit -  ^ breast cancer - disruption of circadian rhythms
  • early circadian testing - use of dim light??
  • recent research - dim light still effects circadian rhythm

SOCIAL CUES

  • meal times, bed times, wake times

TEMP

  • dominant in the absence of light
  • hibernation
6 of 16

Shift work (disruption)

 shift work = disruption of circadian rhythms

  • decreased alertness at night - production of melatonin
  • sleep deprivation - daytime distuptions. decreased REM of 2hrs
  • increased risk of heart disease - Knutson
  • social disruptions - increased divorce rates
  • rotating shifts / forward rotation is good
  • use of artificial lights and melatonin 
  • individual differences - some people unaffected
  • lab experiments - v extraneous variables, also v generalisability
7 of 16

Jet lag (disruption)

Jet lag = disruption of circadian rhythms

  • east to west is best (easier to sleep later than wake earlier)
  • biological rhythms are not equipt to deal with big sudden changes
  • winter et al - recovery - 1 day per hour time difference
  • decreased performance (baseball wins - 44% home, 37% away)
  • effected by other factors (e.g. caffine and alcohol)
  • Melatonin use - Jet lag miracle cure
  • social customs - flight starvation - reset biological clocks
8 of 16

Sleep changes (1)

INFANCY

  • sleep 16hrs per day. v sleep cycle time. ^ REM
  • at one year old infants sleep mainly at night
  • adaptive sleep patterns - ^ survival
  • ^ REM - production of neurotransmitter and consolidation of memory

CHILDHOOD

  • EEG paterns like that of an adult
  • 12hrs sleep, 30% REM
  • parasomnias may occur

Adolescence

  • circadian rhythms change - awake later at night (sleep-phase syndrome)
  • hormonal changes
  • males may organsm and ejaculate in sleep
9 of 16

sleep changes (2)

ADULTHOOD

  • parasomnias decrease
  • disorders such as sleep apnoea and insomnia
  • too much sleep = ^ risk of mortality ( 30% ^ at 10hrs sleep a night). Underlying factors? illness may ^ sleep, and also result in mortality)

OLD AGE

  • wake up more in the night
  • day time naps to compensate waking
  • REM decreases to 20%
  • phase advance syndrome (get up earlier, go to bed earlier)
  • decresed SWS, decreased GH production (symptoms of old age)
10 of 16

Restoration Theory

OSWALD PROPOSED THAT SWS ENABLES BODY REPAIR, REM ENABLES BRAIN RECOVERY

SWS

  • growth hormone secreted (protien synthesis)
  • Sassin et al - SWS reversed -> GH production also reverses
  • suggests GH is controlled by same mechanisms as SWS
  • decresed SWS = decresed immune system (due to decreased protien synth)

REM

  • brain growth - evidence from babies (lots of REM) brain immature at birth
  • REM = break in neurotransmitters = neurones regain sensitivity
  • support from MAIO's - side affect, no REM, as monoamine receptors dont need to be replemished
  • REM IS IMPORTANT FOR CONCOLEDATION OF PROCEDURAL MEMORY
  • during REM, unwanted memories are discarded, making more important memories accessible.
11 of 16

resoration theory commentary

EFFECTS OF TOTAL SLEEP DEPRIVATION

  • PETER TRIPP. case study.
  • microsleep (after 72hrs) non-sleeper gets benefit of sleep
  • studies on rats, fatal consequences, all diead after 33 days. stress may be cause.
  • rattenburg - pigeons had no ill effects

EFFECTS OF PARTIAL DEPRIVATION

  • REM rebound, increased REM the next night
  • Empson - depriving pps of REM, instantly went back to REM after waking
  • recovery nights - 50% more REM

EXERCISE AND NEED FOR SLEEP

  • horne & minard - pp's fell asleep quicker, not for longer
  • marathon runners - 2 hours more sleep after a race
12 of 16

EVOLUTIONARY EXPLAINATION

EVOLUTIONARY EXPLAINATION

  • energy conservation- period of reinforced inactivity
  • foraging- herbivores sleep longer than carnivores
  • predetor avoidance - sleep when predetors are awake, increases survival
  • waste of time (Meddis) - stay out of way when most vulnerable (hidden)
  • siegel agrees - being awake is more risky, noise attracts predetors
  • smaller animals - ^ metabolic rate = ^ sleep needs, Zeplin. (exceptions, sloth)
  • Energy conservationin NREM only - primative reptiles have NREM only
  • REM evolved later to maintain brain activity 
  • Horne suggests Core sleep and Optional sleep
  • Core: requires for essential processes (SWS)
  • optional : dispensable, occupying unproductive hours (REM)
  • Unilateral sleep, evoluationary adaptation. Dolphins, Ducks, etc.
  • evolutionary approach fails to address some key aspects
  • combined approach (evolutionary and restoration) explain all aspects
13 of 16

Insomnia

primary- occured on its own secondary - as a result of underlying condition

Risk factors

  • age - older people - physical problems
  • gender - women - hormonal changes (menopause)
  • personality- internalising distress
  • genetic predisposition - 50% concordance (identical twins)
  • diathesis stress model - vulnerability + stress = insomnia
  • perpetuating factors - e.g. being tense at bed times
  • roberts et al - teen insomnia, 25% had symptoms, of that 41% 1 year later

Treatment of insomnia

  • attribution theory - "stimulant" pill - sleep easier due to attribution of wakefullness blamed on pill, and therefore relaxation occured
  • increasing sleep hygine (healthiness of habits, eg not drink alchohol)
  • use of melatonin
  • sleep restriction - no sleeping outside designated hours
14 of 16

Narcolepsy

NARCOLEPSY

  • symptoms - sleepiness all the time, and cataplexy
  • malfunction in mechanism that controls REM sleep (explains cataplexy)
  • REM hypothesis- vogel. cataplexy is linked to the activation of cells only active in normal animals during REM. But research has not been convincing
  • mutation of HLA (immune system), one variant found in many narcoleptic patients, hovwever, not in all, and is common in general population
  • link between hypocretin and narcolepsy, distuption of hypocretin found in narcoleptic dogs.
  • Nisho, narcoleptics had less hypocretin
  • not likely to be linked genetically , may be due to brain injust, stress, diet or auto-immue attack (this would explain HLA link)
15 of 16

sleep walking

SLEEP WALKING

  • affects about 20% of children
  • occus only in SWS, and is linked to night terrors
  • disorder of arousal - incomplete arousal - abnormal arousal is genetic
  • may be due to stress, fever, or psychiatric conditions
  • oliviero- suggests that SW occurs due to underdevelopment of motor activity that usually inhibits SWS
  • fits in the diathesis stress model
  • 50% concordance in identic twins (diathesis)
  • lack of maturity in neural sleep circuits (stress) 
  • used as a criminal defence - Joules Lowe, killed his father, not guilty due to previous violent SWing and further testing in a sleep lab, condemmed to a psychiatric hospital
  • difficult to diagnose
16 of 16

Comments

No comments have yet been made

Similar Psychology resources:

See all Psychology resources »See all Sleep resources »