biological rhythms

Question 1

circadian rhythms definition

Answer 1

biological rhythms, subject to a 24 hour cycle which regulates a number of body processes such as the sleep wake cycle and changes in body temp

Question 2

what are biological rhythms

Answer 2

distinct patterns of changes in body activity that conform to cyclical time periods influenced by internal body clocks as well as external changes to environment

Question 3

ultradian rhythms

Answer 3

rhythms that occur multiple times throughout the day

Question 4

infradian rhythms

Answer 4

take longer than aday to complete eg menstral cycle is 28 days

Question 5

the sleep wake cycle

Answer 5

the fact that we feel drowsy at night time and more alert during the day is governed by the sleep wake cycle
this is maintained by exogenous zeitgebers and endogenous pacemakers
exogenous- light, we go to sleep when its dark, and social norms
endogenous- superchiasmatic nucleus- lies just above the optic chiasm which provides information about light

Question 6

what can the SCN be reset by

Answer 6

exogenous zeitgebers- light

Question 7

siffre cave study

Answer 7

spent several extended periods underground to study the effects of a lack of light change on his own biological rhythms. sleep wake cycle adjusted to 25 (believed a day was longer than it was) hours rather than 24
still went to sleep and woke up on a regular schedule

Question 8

individual differences

Answer 8

some people prefer to wake up and go to sleep earlier than others, some prefer to wake up and go to sleep later than others

Question 9

wever research

Answer 9

convinced a group of pps to spend four weeks in a ww2 bunker deprived on natural light, circadian rhythm extended to 29hrs

Question 10

strength of circadian rhythms

Answer 10

provides an understanding of adverse consequences that occur when disrupted (desynchronisation)
those who engage in night shift work are more likely to experience a period of reduced concentrtaion at around 6 in the morning
this suggets that using sleep wake research rwa can be formed

Question 11

example of an ultradian cycle

Answer 11

sleep cycle, occurs once every 90 mins when sleeping

Question 12

stage one and two of sleep cycle

Answer 12

light sleep, brain waves are high frequency and low amplitude
person may be easily woken
slight changes are called sleep spindles and wabves at this stage are alpha waves

Question 13

stages 3-4 of the sleep cycle

Answer 13

deep sleep, slow wave sleep, brain waves are less frequent and amplitude is higher. harder to wake. delta waves.

Question 14

stage 5 of the sleep cycle

Answer 14

REM (rapid eye movement) theta waves produced and eyes move around.

Question 15

exogeneous zeitgebers AO1

Answer 15

• Light is a key zeitgeber is humans, it can reset the body’s pacemaker SCN
• Light also has a key role in indirect processes such as blood circulation and hormone secretion
• MURPHY research- aimed to determine whether light was still an EZ when not detected by eyes. shone a light on the back of peoples kneecaps at random points in the night to wake them up. this caused a deviation of up to 3hrs in original sleep cycles.
  -social cues, the social expectation to go to sleep at night, being told by parents since birth by 16 weeks the imposed schedule from parents becomes and innate system.

Question 16

endogenous pacemakers AO1

Answer 16

• the superchiasmatic nucleus is the body’s innate clock and is a tiny bunch of nerve cells located in the hypothalamus in each hemisphere of the brain the SCN lines just above the optic chiasm so recieves messages about light .

Question 17

endogenous pacemakers AO1 animal studies

Answer 17

DeCoursey, 30 chipmunks had SCN connections destroyed and were then returned to natural habitat and observed for eighty days. sleep wake cycle had been destroyed and a majority of them had been attacked or killed because they were awake and vunerable when predators could attack.
Ralph- mutant hamsters study bred mutant hamsters with 20 hour sleep cycle when foetal tissue removed and implanted into normal hamsters their SCN reset to 20 hrs

Question 18

limitations endogenous pacemakers

Answer 18

• use of animal studies hard to generalise to humans, hamsters are nocternal so already have very different sleep wake cycles and have much smaller, simpler brains
• should be an interactionist system, siffres cave study, still had artcificial lamp with him which may have reset his SCN in daily life pacemakers and zeitgebers interact so shouldnt be studied in isolation because this lacks ecological validity.

Question 19

limitations of exogenous zeitgebers

Answer 19

• do not have same effect in all environments people live in environments with very little light in summer and little darkness eg arctic circle and have similar sleeping patterns despite spending six months in darkness this challenges the impact of light on the SCN and sleep wake cycle
• another limitation is that evidence challengers the role of social cues. blind man born with longer sleep wake cycle than most people (24.9h) despite exposure to social cues couldnt be adjusted