biological rhythms- circadian rhythms

Question 1

circadian rhythm:

endogenous pacemaker:

exogenous zeitgebers:

Answer 1

24 hours (body clock) reset by levels of light. Includes sleep wave and body temperature.

internal factors (bodies biological clock)

external factors (changes in the environment)

Question 2

how the circadian rhythm works

Answer 2

light is detected by the eye which sends a message to suprachiasmatic nucleus (SCN), which then uses this information to coordinate activity of entire circadian rhythm.

Question 3

case study:

Answer 3

there was evidence found for ‘free running’ circadian rhythm. On several occasions a man lived underground with no external cues to guide his rhythms. He woke up, ate and slept when he felt it was appropriate to.

after being underground for 61 days he resurfaced believing it was a month earlier than it was.

he stayed in a cave 30 years later as he was interested in seeing what the effect age had on circadian rhythms. He found it ticked more slowly when he was older.

Question 4

AO3: limitation- case study

however, other studies show the same findings

Answer 4

P: the study was a case study
E/E: this means it was only based on one person and can’t be generalised to the target population. He also could not repeat the experiment meaning consistency could not be checked.
L: this means research into circadian rhythms is low in population validity
HOWEVER,
another study was done with multiple participants where they were in bunkers and the only source of light was artificial. After staying in the bunker the participants settled into a 25-27 sleep cycle. This demonstrates the importance of light for the circadian rhythm. As well as showing the same findings have been found with more participants when it comes to research into circadian rhythms

Question 5

limitation- individual differences

Answer 5

P: individual differences aren’t considered
E: people prefer going to bed and waking up at different times.
E: demonstrates that there may be innate individual differences in circadian rhythms.
L: researches should focus on these individual differences when it comes to circadian rhythms.

Question 6

strength- real world applications

Answer 6

P: real world application of chronotherapeutics
E: chrontherapeutics is the study of how time affects drug treatment. The time taken of a drug effects the drugs success.
E: for example risk of heart attack is greatest during early morning hours, so chronotherapeutic medications have been developed to be taken before the person goes to sleep, then the drug is released at the vulnerable period (6am to noon).
L: shows the research into circadian rhythms has helped the effectiveness of drug treatments

Question 7

limitation- temperature may be more important than light

Answer 7

P: temp may be more important than light in determining circadian rhythms.
E/E: found that fluctuations in temp set the timings of cells in the body and caused tissues and organs to become active or inactive. Body temp fluctuates on a 24 hour circadian rhythm and even small changes in it can sent a powerful signal to our body clocks.
L: this show that a more holistic approach should be taken when it comes to circadian rhythms