biological rhythms

Question 1

what is a biological rhythm?

Answer 1

a cyclical period where a distinct pattern of change happens within the body. they’re influenced b our internal body clocks (endogenous pacemakers) and external environmental changes (exogenous zeitgebers)

Question 2

what is the circadian rhythm?

Answer 2

AKA the ‘body-clock’ operates on 24 hours cycle which is reset by levels of light e.g sleep-wake. physical or psychological activity that occur about once a day

Question 3

example of circadian rhythm?

Answer 3

sleep-wake cycle

Question 4

what is the circadian rhythm primarily controlled by?

Answer 4

suprachiasmatic nucleus (SCN) which is an endogenous pacemaker

Question 5

what is an endogenous pacemaker (EP)

Answer 5

internal biological clocks that regulate rhythm e.g sleep-wake, temperature

Question 6

what can endogenous pacemakers be disrupted by?

Answer 6

exogenous Zeitgebers e.g light, caffeine and noise

Question 7

what was the aim of siffre case study?

Answer 7

aimed to test his ‘free running’ body clock and how natural rhythms in the body work when he lived underground in a cave for extended periods of time

Question 8

what was siffre procedure?

Answer 8

• case study of one individual
• spent 61 days in the southern alps with no natural light, sound, clocks or calendars
• he had an artificial lamp and a corded phone
• he slept and ate when his body told him to and measured his physiology throughout
• this allowed his ‘free running’ body clock to control his behaviour

Question 9

what were the results of his procedure?

Answer 9

his ‘free running’ body clock had increased to 25 hours making his day seem longer (sleep less, awake longer). aged 60 he replicated his study and found that his internal body clock increased to 36-48 hours

Question 10

what can we conclude from this research?

Answer 10

light plays an important role in circadian rhythms and demonstrates a free running circadian rhythm of about 25 hours

Question 11

how does siffre research support circadian rhythms?

Answer 11

supports the idea that the sleep-wake cycle has a duration of just over 24 hours- interference is likely to be detrimental to functioning

Question 12

what is a limitation of siffre research?

Answer 12

only included one participant- himself. meaning results cannot be generalised and results may have lost objectivity due to misinterpretation or confirmation bias

Question 13

what are infradian rhythms?

Answer 13

cycles that lasts more than 24 hours e.g menstrual cycle

Question 14

what is the menstrual cycle?

Answer 14

rising oestrogen levels cause the egg to be released from a ovary, egg travel down oviduct to the womb. rising progesterone levels thicken the lining of the womb if egg is not fertilised the lining will shed

Question 15

what is SAD?

Answer 15

seasonal affective disorder, tends to hit people during the winter months when the days are longer and darker

Question 16

why does SAD usually affect people in the winter?

Answer 16

in winter melatonin is secreted which may result in higher levels of depression or a generalised low mood

Question 17

summarise mclinktock and sterns research into infradian rhythms

Answer 17

29 women in the study given samples of pheromones from the armpits of women in study to inhale. samples taken throughout their menstrual cycle

Question 18

mclinktock and stern study findings

Answer 18

68% of participants found that their menstrual cycle had aligned with their donor

Question 19

what was Rosen et als research into SAD

Answer 19

large scale survey of adults who lived in one of four different sates (New Hampshire, New York, Maryland, Florida) research measured prevalence rates of winter SAD and summer SAD

Question 20

what were Rosen et als findings into SAD?

Answer 20

found winter SAD rates were significantly higher the more northern the state was.
no correlation was found between N/S states and summer SAD
highest prevelance= winter SAD age over 35

Question 21

what was the conclusion of Rosen et alls study into SAD?

Answer 21

concluded that living at a more northern latitude (longer and darker days) Is likely to lead to SAD

Question 22

what is a strength of Mclinktock and Sterns research?

Answer 22

longitudinal field study, therefore changes over time could be tracked, increases validity of findings

Question 23

what is a limitation of Mclinktock and Sterns research?

Answer 23

extraneous variables such as the women’s diet, nutrition, exercise regime

Question 24

what is a strength of Rosen et al study?

Answer 24

large scale survey= good reliability, used standardise questionnaires to generate quantitative data, could be repeated with with different populations

Question 25

what is a limitation of Rosen et al study?

Answer 25

conducting a large scale survey into SAD lack explanatory power- not clear why sad occurs in northern states and other reasons such as life events

Question 26

what are ultradian rhythms?

Answer 26

cycles which occur under 24 hour cycles e.g human sleep cycle

Question 27

how many stages of sleep are there?

Answer 27

5 recognised stages of sleep

Question 28

what does stage 1 and 2 consist of?

Answer 28

also known as sleep escalator, 'light sleep', slow and rhythmic alpha waves (tracked using EEG), sleep spindles appear to diminish response to outside stimuli while asleep

Question 29

what doe theta waves show when an individual is asleep?

Answer 29

they have gone into a deeper sleep

Question 30

what does stage 3 and 4 consist of?

Answer 30

consists of delta waves of deep sleep- greater amplitude, difficult to wake sleeper

Question 31

what does stage 5 consist of?

Answer 31

REM sleep (rapid eye movement), where dreaming occurs, the CNS is 'cut off'- essentially paralysing the body as dreaming occurs. brain activity speeds up- showing similar levels of energy to the awake brain

Question 32

what are stage 1-4 categorised as?

Answer 32

NREM (non rapid eye movement), approximately 75% to 80% of sleep time is spent in NREM, dreaming can occur but is more common in REM stage

Question 33

what did dement and kleitman research?

Answer 33

made the link between rem sleep and dreams

Question 34

what was dement and kleitmans research?

Answer 34

- 5 participants studied intensively and taken to sleep lab -told not to drink alcohol caffeine before experiment - EEG machine was used to track their brainwaves during sleep - woken at specific intervals during sleep and asked if they were dreaming if so what about?

Question 35

what were dement and kleitmans findings?

Answer 35

findings showed a positive correlation between between REM and dreaming, the nature of dreams matched their eye movements. e.g vertical eye movements: occurred w/ dreams of climbing, ladders, watching climbers horizontal eye movements: occurred with dreams of watching people throw tomatoes at each other

Question 36

what is are strengths of dement and kleitmans research?

Answer 36

conducted a well controlled study w/ extra care taken to eliminate possible confounding variables = high in reliability replications have supported findings

Question 37

what are limitations of dement and kleitmans research?

Answer 37

lack of generalisability and external validity, only 5 participants, larger sample would have increased robustness of data lack of temporal validity study conducted in 1950's e.g digital technology may now interfere with ultradian rhythms