PHYSIOLOGICAL PSYCHOLOGY

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PHYSIOLOGICAL PSYCHOLOGY

• BIOLOGICAL RHYTHMS
• SLEEP
• DREAMING

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BIOLOGICAL RHYTHMS

• Organisms have a biological clock, which is
  regulated by
• Endogenous pacemakers internal mechanisms, e.g.
  sleeping and waking
• Exogenous zeitgebers external factors, e.g.
  night and day

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CIRCADIAN RHYTHMS

• Circadian Circa - about (Latin)
• Dia day
• Rhythm repeats itself every 24 hours, e.g.
• Body temperature peaks in the late afternoon and
  dips in the early hours.
• Sleep/wake cycle hormones are released from the
  pituitary gland.

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ULTRADIAN RHYTHMS

• Ultradian
• Rhythm repeats more than once a day. (Ultra
  lots) e.g. when we sleep we go through different
  phases. Each cycle lasts about 90 minutes

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INFRADIAN AND CIRCANNUAL RHYTHMS

• Infradian
• Rhythm repeats less than once a day, e.g.
  menstrual cycle
• Circannual
• Rhythm repeats once a year, e.g. hibernation,
  migration, shedding hair and fur.

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SLEEP-WAKING CYCLE

• This is regulated by the exogenous zeitgeber of
  light and dark.
• Psychologists are interested in whether cycles
  depend more on
• ENDOGENOUS PACEMAKERS
• OR
• EXOGENOUS ZEITGEBERS

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RESEARCH STUDIES

• SIFFRE spent 2 months in a dark cave. He
  developed a 25 hour cycle.
• WEVER 79 studies on Ps who spent weeks in
  isolation bunkers. Again, cycle adjusted to 25
  hours, though in some cases 30 hours.
• An endogenous clock therefore exists.

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TASK Draw arrows to link correctly
P.80/170THE PROCESS OF FALLING ASLEEP

• Sleep Optic chiasm protein synthesis
• Occurs receives light in SCN fluctuates
• Signals

Rhythm of protein production stimulates Pineal
gland
Melatonin is Produced
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FUNCTION OF SUPRA-CHIASMATIC NUCLEUS (SCN)

• MORGAN removed SCN from hamsters. Circadian
  rhythms disappeared, but reappeared if foetal SCN
  cells were transplanted.
• TASK Read Sleep and Melatonin p.81/171.
• Fill in the gap and answer the question
• The greatest propensity to fall asleep is called
  the ______ _______.
• How can insomniacs be treated for their condition?

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EXOGENOUS FACTORS

• MILES study of a man blind from birth. He
  needed stimulants and sedatives to co-ordinate
  with the rest of the world, as he could not
  respond to the zeitgeber of light.
• Exogenous factors therefore seem crucial
• BUT
• LUCE AND SEGAL 66 found that Arctic dwellers
  sleep for 7 hours, even in summer.
• Therefore endogenous factors AND exogenous
  factors can be overridden.
• External factors animals need to adjust to
  changes in temperature and light, as it is vital
  for their survival.

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ENDOGENOUS FACTORS

• EYSENCK 82 found that performance on most
  tasks peaks at midday.
• Find reasons for this p.83/173
• Self-reported alertness and levels of adrenaline
  peak at midday. Reduction of performance often
  occurs after lunch, when the parasympathetic
  branch of the nervous system controls digestion
  and relaxes the body

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MENSTRUAL CYCLE (INFRADIAN)

• Governed by hormones (an endogenous mechanism)
• 28 days in humans, varies in other mammals.
• Cycle is governed by the hormones oestrogen and
  progesterone which cause the lining of the womb
  to become engorged with blood. If egg is not
  fertilised, womb lining is shed as a period.

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Effect of external factors

• REINBERG documented a womans cycle when she
  spent 3 months in a cave. The menstrual cycle
  was shortened, and sleep/wake cycle lengthened.
• This implies that light affects menstrual cycle

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PHEROMONES

• EXOGENOUS CONTROL of the menstrual cycle also
  seems to occur in the presence of other women.
• McCLINTOCK 71 observed that girls at boarding
  school, and nuns have synchronised cycles.
• He suggested that this was due to PHEROMONES,
  biological substances which are released in the
  air and carry messages
• TASK find out what possible evolutionary
  advantage this could have (p.84/174)

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CIRCANNUAL RHYTHM

• CIRCANNUAL RHYTHM
• PENGELLEY AND FISHER 57 put a squirrel in
  artificial light for 12 hours per day at 0C.
• The animal hibernated from Oct-April and body
  temperature dropped from 37 to 1C.
• Hibernation appears to be endogenously
  controlled.

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MIGRATION

• This is thought to be triggered by a change in
  day length and/or food supply (external factors)
• BUT
• GWINNER kept wild birds for 3 years and
  maintained a constant 12 hours of light and dark.
• The birds showed migratory restlessness.
• Migration therefore appears to be endogenous.
•  

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SEASONAL AFFECTIVE DISORDER

• Depression in winter. Some people get it in
  summer.
• BARLOW AND DURAND 95 proposed that extra
  melatonin production in low light affects
  serotonin.
• It is more common in the north of the northern
  hemisphere. For example,
•  

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SAD

• TERMAN 88 found
• 10 of population suffered in New Hampshire
• 2 of population suffered in Florida (sunny)
• PHOTOTHERAPY is recommended in order to suppress
  melatonin production

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LESSON OBJECTIVES

• What happens when we disrupt our biological
  rhythms?
• Evidence from
• Jetlag
• Shiftwork

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DISRUPTION OF BIOLOGICAL RHYTHMS 

• JETLAG P.175
• Does not occur if travelling
• north south.
• Easier to adjust if travelling
• west. 
• KLEIN et al this is because
• the day is lengthened , and
• we have a tendency to lengthen
• our cycle. 

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PHASE ADVANCE AND PHASE DELAY

• PHASE DELAY is easier than PHASE ADVANCE 
• Similarly, it is easier to stay up late than go
  to bed early. 
• SCHWARTZ 95 analysed results of American
  baseball games where teams travelled across
  America (3 hours difference) 
• West coast teams EAST fewer
  wins
• East coast teams WEST more wins

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EVALUATION

• (BUT east coast teams may have simply been better
  players)
• Melatonin can combat jetlag. It is recommended
  to adapt to new time immediately.
• TASK read Melatonin and Aircrew box p.176
•  

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SHIFTWORK
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SHIFTWORK

• 20 of the population works shifts. 
• More accidents occur at night
• CHERNOBYL
• BHOPAL
• THRE MILE ISLAND
•  All occurred between 1-4am
• Most lorry accidents occur between 4-7 am. 
• There are ways of improving shiftwork patterns.

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MONK AND FOLKARD 83

• identified 2 types of shift
• 1.      Rapidly rotating 1-2 shifts then change
• 2.      Slowly rotating change of shift every
  week or month.
• 1 is thought to be better, because 2 causes major
  changes to circadian rhythm.
• But 1 causes constant disruption to circadian
  rhythm

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DAWSON AND CAMPBELL

• used bright lights which helped shiftworkers to
  work better. This may substitute sunlight and
  reset SCN
• CZEISLER 82 tested phase delay and phase
  advance in changing shifts. Workers felt much
  better in phase delay, i.e.
• EARLY LATE NIGHT  
• This resulted in fewer errors and higher
  productivity