1.3 Biopsychology (Biological Rhythms)

Question 1

What are biological rhythms?

Answer 1

Distinct patterns of changes in body activity that conform to cyclical time periods

Question 2

What is a circadian rhythm and give an example?

Answer 2

A biological rhythm, subject to a 24 hour cycle which regulate a number of body processes e.g sleep-wake cycle

Question 3

What 2 factors influence biological rhythms?

Answer 3

• Endogenous pacemakers: the bodys internal biological ‘clock’
• Exogenous zeitgebers: External changes in the environment

Question 4

What are the 3 biological rhythms?

Answer 4

• Circadian rhythms
• Infradian rhythms
• Ultradian rhythms

Question 5

What endogenous pacemaker influences the sleep-wake cycle and what does it do?

Answer 5

Suprachiasmatic nucleus (SCN): provides information from the eye about light (exogenous zeitgebers e.g light can reset the SCN)

Question 6

Describe Siffres cave study

Answer 6

• Spent several extended periods underground to study effects on his own biological rhythms
• He was deprived of exposure to natural light and sound
• Kept a diary of his sleep and wake patterns (sleep was initially erratic but settled to a normal rhythm)
• His natural circadian rhythm was 25 hours
• Spent two months in the cave but according to his record he had only been there for 1.5 months

Question 7

Describe Folkard et al (1985) research on exogenous zeitgebers

Answer 7

• Studied influence of exogenous zeitgebers on internal biological clock
• 12 people agreed to live in a cave for 3 weeks
• Went to bed when clock said 11:45 and woke up 7:45
• Over time, researchers gradually sped up clock (so typical 24 hour day only lasted 22 hours)
• Only one participant was able to comfortably adjust
• Suggests existence of of strong free-running rhythm that cannot be overridden by exogenous zeitgebers

Question 8

AO3 for circadian rhythms

Answer 8

1. Shift work: understanding of consequences when rhythms disrupted (desynchronisation), Boivin et al (1996) night workers engaged in shift work experience a period of reduced concentration around 6 in the morning meaning mistakes/accidents more likely, also research points to relationship between shift work and poor health, Knutsson (2003) shift workers three times more likely to develop heart disease than those who work typical work patterns, research has real-world economic implications in how to manage worker productivity

2. Medical treatment: used for improvements in treatment, rhythms coordinate a number of body’s basic processes e.g digestion and hormone levels, led to field of chronotherapeutics (how medical treatments can be administered in way that corresponds to biological rhythms), e.g aspirin which reduces blood platelet activity to prevent heart attacks most effective if taken last thing at night, Bonten et al (2015) evidence that heart attacks most likely to occur in the morning

3. Individual differences: generalisations difficult to make, most research e.g Siffre based on very small sample of participants, seems that sleep-wake cycles vary from person to person, Czeisler et al (1999) found individual differences in sleep-wake cycles varying from 13 to 65 hours, also Duffy et al (2001) revealed some have natural preference for going to bed and rising early whereas some are the opposite, Siffre himself in a later study observed that his own sleep-wake cycle has slowed down since he was young, difficult to use research data to discuss anything more than averages

Question 9

What is an infradian rhythm and two examples?

Answer 9

A type of biological rhythm with a frequency of less than one cycle in 24 hours e.g menstrual cycle, SAD

Question 10

What is ultradian rhythm and one example?

Answer 10

A type of biological rhythm with a frequency of more than one cycle in 24 hours e.g the sleep cycle

Question 11

What is the menstrual cycle?

Answer 11

• A type of infradian rhythm governed by monthly changes in hormone levels which regulate ovulation (takes approximately 28 days to complete)

Question 12

Describe Stern and McClintock’s (1998) research into synchronisation of menstrual cycle

Answer 12

• Studied how menstrual cycles may synchronise as a result of phermones
• Studied 29 women with a history of irregular periods
• Phermones of women gathered from 9 of the women at different stages of their menstrual cycle via cotton pad in their armpit
• Pads worn for 8 hours and then rubbed on upper lip of other participants
• On day one, pads from start of menstrual cycle applied to all women and so on
• Found 68% experienced changes to cycle which brought them closer to cycle of ‘odour donor’

Question 13

What is seasonal affective disorder (SAD) and its symptoms?

Answer 13

A depressive disorder which has a seasonal pattern, symptoms are triggered by winter months where daylight hours become shorter e.g persistent low mood, lack of activity and interest in life

Question 14

Why can seasonal affective disorder (SAD) also be classed as a circadian rhythm?

Answer 14

Experience of SAD may be due to disruption of sleep-wake cycle due to prolonged periods of darkness during winter

Question 15

What is the role of melatonin in seasonal affective disorder (SAD)?

Answer 15

During night, pineal gland secretes melatonin until dawn when there is an increase in light. However, during winter the lack of light in the morning means this secretion process is longer

Question 16

How long does the sleep cycle last and how can the stages be monitored?

Answer 16

• Spans for approximately 90 minutes
• Each stage is characterised by different level of brainwave activity, monitored through EEGs

Question 17

Describe the stages of sleep

Answer 17

• Stages 1 and 2: light sleep where person can easily be woken, stage 1 brain waves have high frequency and short amplitude (alpha waves), stage 2 alpha waves continue but random changes in pattern called sleep spindles
• Stages 3 and 4: known as deep sleep or slow wave sleep (SWS), brainwaves are delta waves with lower frequency and higher amplitude, difficult to wake someone at this point
• Stage 5 (REM): body is paralysed but brain activity resembles awake brain, brain produces theta waves and there is rapid eye movement (also when dreams most likely)

Question 18

Describe the process of the menstrual cycle

Answer 18

• During the cycle, rising levels of oestrogen cause ovary to develop and release an egg (ovulation)
• After ovulation, progesterone helps the womb lining grow thicker to ready the womb for pregnancy
• If pregnancy does not occur, the egg is absorbed into the body and the womb lining comes away and leaves the body (menstrual flow)

Question 19

What is the role of melatonin?

Answer 19

A chemical produced by the brain and responsible for the timing of the circadian rhythm (important in falling asleep, staying asleep and waking up)

Question 20

AO3 for infradian rhythms

Answer 20

1. Evolutionary basis: menstrual synchrony may be explained by natural selection, for our distant ancestors it may have been advantagous for women to menstruate and become pregnant together, allowed babies who had lost their mothers due to childbirth to have access to breast milk which improved their chances of survival, synchronisation has adaptive strategy

2. Methodological limitations: many factors that may effect change to menstrual cycle e.g stress, changes in diet, exercise, these act as confounding variables, may mean that supposed pattern of synchronisation would have been expected to occur by chance, may explain why other studies may not be able to replicate studies therefore menstrual synchrony studies are flawed

Question 21

AO3 for ultradian rhythms

Answer 21

1. Improved understanding: helped understanding of age related changes in sleep, sleep scientists have observed SWS reduces with age, growth hormone is mostly produced in SWS therefore reduced in older people, Cauter et al (2000) this sleep deficit may explain various issues in old age e.g reduced alertness, in order to increase SWS relaxation and medication may be used, knowledge of ultradian rhythms has practical value

2. Individual differences: significant variation between people, Tucker et al (2007) found large differences between participants in terms of duration of each sleep stage particularly stages 3 and 4 and suggested these differences were biologically determined, difficult to describe ‘normal sleep’ in a meaningful way

Question 22

What are endogenous pacemakers?

Answer 22

Internal body clocks and mechanisms that regulate many of our biological rhythms

Question 23

What are exogenous zeitgebers?

Answer 23

External environmental cues that affect and entrain our biological rhythms

Question 24

What is the SCN?

Answer 24

A tiny bundle of nerve cells, located in the hypothalamus of each hemisphere which enables the biological clock to adjust to changing patterns of daylight while asleep

Question 25

Descrine DeCoursey et al (2000) research on animal studies and the SCN

Answer 25

• Destroyed SCN connections in the brains of 30 chipmunks
• After, returned to their natural habitat and observed for 80 days
• The sleep-wake cycle of the chipmunks disappeared and by the end most had been killed by predators
• Due to them being awake, active and vulnerable to attack
• Shows the influence of SCN on maintaining circadian rhythm in animals

Question 26

What is entrainment?

Answer 26

The process of coordinating the internal circadian clock to external rhythmic time-cues

Question 27

What did Campbell and Murphy (1998) discover about light as exogenous zeitgeber?

Answer 27

• Demonstrated that light can be detected by skin receptor sites on the body even when same information is not received by the eyes
• 15 participants woken at various times and light pad shone on back of their knees
• Researchers produced a deviation in usual sleep/wake cycle
• Suggests light as powerful exogenous zeitgeber, that does not depend on eyes to exert influence

Question 28

How can social cues affect jet lag?

Answer 28

Adapting to local times for eating and sleeping (rather than responding to ones own feelings of hunger and fatigue) is effective in entraining circadian rhythms

Question 29

How do social cues affect circadian rhythms of babies?

Answer 29

By 16 weeks, babies circadian rhythms have been entrained by schedules imposed by parents e.g adult determined meal and bed times

Question 30

AO3 for endogenous pacemakers

Answer 30

1. Beyond the master clock: SCN research may obscure other body clocks, research revealed numerous circadian rhythms in many organs and cells in the body, these peripheral oscillators are influenced by actions of SCN but also act independently, Damiola et al (2000) demonstrated how feeding patterns in mice could alter circadian rhythms of cells in the liver by up to 12 hours whilst rhythm of SCN unaffected, suggests other complex influences on sleep-wake cycle

2. Interactionist system: endogenous pacemakers cannot be studied in isolation, total isolation studies e.g SIffre are extremely rare, also Siffre used artifical light which may have reset his biological clock every time it was turned on, in everyday life pacemakers and zeitgebers interact and may make little sense to separate the two for research purpose, suggests the more researchers attempt to isolate the influence of internal pacemakers the lower the validity of the research

Question 31

AO3 for exogenous zeitgebers

Answer 31

1. Environmental observations: exogenous zeitgebers do not have the same effect in all environments, e.g people who live within the arctic circle have similar patterns all-year round despite spending around six months in total darkness, suggests sleep/wake cycle is primarily controlled by endogenous pacemakers that override environmental changes in light

2. Case study evidence: evidence challenges role of exogenous zeitgebers, Miles et al (1977) recounted the study of a young man, blind from birth who had circadian rhythm of 24.9 hours, despite exposure to social cues such as regular meal times his sleep/wake cycle could not be adjusted, suggests social cues alone are not effective in resetting biological rhythms