Biological Rhythms

Question 1

What is meant by a circadian rhythms?

Answer 1

They are biological rhythms that last a day (approx 24 hours)

Question 2

What is an example of a circadian rhythm?

Answer 2

The sleep / wake cycle

Question 3

What is the sleep I wake cycle regulated by?

Answer 3

• Regulated by internal systems including hormones, metabolic rate and body temp.

Question 4

what kind of hormone regulates the sleep/ wake cycle ?

Answer 4

melatonin

Question 5

describe the case study carried out by Siffre

Answer 5

• case study on himself
• spent 6 months in a cave with no natural light or cues as to the day or time
• when he woke up he had artificial light to help him navigate within the cave an keep himself busy
• his internal body clock was allowed to free-run

Question 6

describe the findings of Siffre’s case study

Answer 6

• his internal body clock settled into a sleep/wake cycle of between 25 and 30 hours
• he lost track of how many days he had been in the cave, believing it to be 1 month less than he had actually stayed in

Question 7

how many days was Siffre in the cave for ?

Answer 7

179 days

Question 8

what did Siffre’s case study suggest ?

Answer 8

• this suggests that the natural light sources in the environment are vital for keeping the individual to a 24 hour cycle

Question 9

Describe the research carried out by Folkard ?

Answer 9

• withdrew ps from natural light for 3 weeks
• changed the time cues to only 22 hours a day without the ps being aware that that occurred

Question 10

what were the findings of Folkard’s study ?

Answer 10

• only 1 of the ps was able to adjust to the new regime
• the other 11 were unable to adjust to the shortened day

Question 11

What do Folkard’s findings suggest ?

Answer 11

• they show that our natural circadian rhythm is not flexible and can differ between individuals

Question 12

what are the factors that can affect the sleep/wale cycle ?

Answer 12

• the SCN + sleep
• homeostasis + sleep
• temp + circadian rhythm

Question 13

The SCN + sleep

Answer 13

• light is first detected by the eye , which then sends messages concerning the level of brightness to the SCN
• the SCN then uses this info to coordinate the activity of the entire circadian system

Question 14

Homeostasis + sleep

Answer 14

• when an individual has been awake for a long time, homeostasis tells the body that there is a need for sleep because of energy consumption
• this homeostatic drive for sleep increases throughout the day reaching its maximum in the late evening, when most people fall asleep

Question 15

temp + circadian rhythm

Answer 15

• human body temp is at its lowest in the early hours of the morning and at its highest in the early evening
• sleep typically occurs when the core temperature starts to drop and the body temp starts to rise towards the end of a sleep cycle promoting feelings of alertness 1st thing in the morning

Question 16

what is the human body temp at 4:30 am ?

Answer 16

36 degrees celsius

Question 17

what is the human body temp at 6pm ?

Answer 17

38 degrees celsius

Question 18

AO3
- use of case studies and small samples

Answer 18

• studies tend to involve small groups of ps so the people may not be representative of the whole population so meaningful generalisations cannot be made
• also because small groups are used, there is a possibility of individual differences affecting the results as individual sleep cycles vary with age

Question 19

AO3
- issues of the research methodology

Answer 19

• in Siffre’s research, although he was deprived of natural light, he still had access to artificial light as he turned a lamp on every morning
• he assumed that artificial light has no affect but later studies showed hat they were able to adjust ps biological rhythm using dim lighting
• so the use of light may be analogous to ps taking a drug that resets their biological clock

Question 20

what is meant by ultra-radian rhythms ?

Answer 20

• biological rhythms that last less than 24 hours

Question 21

describe what occurs in stages 1 + 2 of the sleep cycle ?

Answer 21

• light sleep where the person may be easily woken
• brainwave patterns start to become slower and more rhythmic (alpha waves), becoming even slower as sleep becomes deeper ( theta waves )
• sense of falling

Question 22

describe what occurs during stages 3 + 4 in the sleep cycle ?

Answer 22

• involve delta waves which are slower and have a greater amplitude than earlier wave patterns
• this is deep sleep or slow wave sleep
• difficult to wake someone up
• body repairs itself

Question 23

describe what occurs during stage 5 of the sleep cycle ?

Answer 23

• body is paralyzed yet brain activity speeds up significantly in a manner that resembles the wake brain
• REM = rapid eye movement
• research has suggested that REM activity sleep is highly correlated with the experience of dreaming
• then sleep cycle repeats

Question 24

how are the sleep stages measured ?

Answer 24

• they are measured using brain wave activity which can be monitored using an EEG

Question 25

what is a basic rest activity cycle ?

Answer 25

- 90 minute rhythm cycle which continues during the wake hours - characterized by a period of alertness followed by a spell of physiological fatigue

Question 26

describe the research to support the basic rest activity cycle ?

Answer 26

Anectodal evidence - Ericson et al - found that best performers tended to practice for 3 sessions during the course of the day, each session lasted no more than 90 minute + a break to recharge

Question 27

define what is meant by an infraradian rhythm ?

Answer 27

- biological rhythms lasting more than 24 hours

Question 28

what is an example of an infraradian rhythm ?

Answer 28

the menstrual cycle dictated by the endocrine system - using hormones such as oestrogen or progesterone

Question 29

McClintock + Stern research

Answer 29

notes blurt

Question 30

describe the research carried out by Reinberg

Answer 30

- involved a woman spending 3 months in a cave with only the light of a small lamp

Question 31

describe the findings of Reinberg's study ?

Answer 31

- her days lengthened to 24,9 hours and her menstrual cycle shortened to 25.7 days

Question 32

what does Reinberg's study suggest ?

Answer 32

it shows that the levels of light in the cave could have affected the womans menstrual cycle - after the study it took the woman a whole year to readjust her menstrual cycle - this shows that the infraradian biological rhythms can be influenced by external zeitgebers such as light

Question 33

AO3 the effects of pheromones can help explain menstrual synchronicity

Answer 33

the idea of communication via pheromones can explain this as there must be something in the shared environment

Question 34

AO3 evolutionary advantage

Answer 34

- it means there could be synchronised pregnancies and that means that childcare could be shared when babies are born at / around the same time

Question 35

AO3 time requirement for synchronisation is not clear

Answer 35

- how close women have to live together and for what period of time for menstrual synchronisation to occur is not clear, the extent to which pheromones can have an effect still requires research