biopsych- biological rhythms

Question 1

define biological rhythms

Answer 1

biological rhythms are are cyclical changes in the way the biological systems behave
the rhythms have evolved due to the environment

Question 2

define circadian rhythms

Answer 2

circadian rhymths are patterns of behaviour that occur and recur every 24 hours which is set and reset by environmental light levels

Question 3

define the sleep wakes cycle

Answer 3

the alternating states of sleep and waking which depends on the circadian rhythm

Question 4

name the 2 internal influences of the sleep wake cycle ( which is 8 hours of sleep and 16 hours of daytime wakefulness)

Answer 4

• Sleep homeostasis
• Circadian rhythms

Question 5

what do the circadian rhythms depend on

Answer 5

depends of light being the primary input then this sends a signal to the suprachiasmatic nucleus (SCN) which is found in the hypothalamus

Question 6

what is the main example of a biological rhythm

Answer 6

circadian rhythm is the main example of a biological rhythm.

Question 7

name 3 examples of a circadian rhythm
and why are they circadian rhythms

Answer 7

• sleep wake cycle
• body temperature
• hormone production
  all three are circadian rhythms because they all rely of the 24 hour body clock which is reset by LIGHT

Question 8

how does sleep wake cycle work (which is a circadian rhythms)
explain in 3 bullet points

Answer 8

• Light provides the primary input to the system
• Light is detected by the eye which sends messages in relation of brightness, to the SCN the suprachiasmatic nucleus and that is found in the hypothalamus
• The SCN uses this info to coordinate the activity of the entire circadian system.

Question 9

how does the body temperature cycle work ( a circadian rhythm)
explain in three bullet points

Answer 9

• Human body temperature is at it’s lowest in the early hours of the morning (4.30 am) at 36 degree c
• It is the highest body temperature in the evening at (6 pm)
• Then sleep occurs when the temperature begins to drop, and it begins to rise near the end of sleep, which promotes feelings of alertness in the morning

Question 10

name the two things, biological rhythms are regulated by

Answer 10

• exogenous zeitgebers
• endogenous pacemakers

Question 11

what is an example of exogenous zeitgeber
and what is an example of a endogenous pacemaker

Answer 11

exo example is an external cue such as light or social queues
endo example is an internal cue such as the SCN (suprachiasmatic nucleus)

Question 12

define an exogenous zeitgeber

Answer 12

an exogenous zeitgeber is described as environmental events that are responsible for resetting the biological clock of an organism
External Cues such as low levels of light or social cues

Question 13

define an endogenous pacemaker

Answer 13

an endogenous pacemaker are internal mechanisms that govern biological rhythms such as the sleep wake cycle (so what activates this cycle)
Internal Cues such as the SCN which is linked to the pineal gland

Question 14

explain the most important endogenous pacemaker and how it works

Answer 14

the most important is the endogenous pacemaker is the Suprachaismatic nucleus (SCN)
-It is in the hypothalamus and when it is dark the SCN receives information about light (which is an exogenous zeitgeber) via the optic nerve.
-This then sends a signal to the pineal gland, which increases the levels melatonin at night, this hormone encourages sleepiness

Question 15

Evaluating endo and exo on the sleep wake cycle

para 1
research support for the role of exogenous zeitgebers on sleep wake cycle
study by S…… 1975
cas. ….y and it was in a c…… for mont..

Answer 15

Research Support: to investigate circadian rhythms and the effect of external cues like light (exogenous zeitgeber)
- Siffre (1975) found that the absence of external cues significantly altered his circadian rhythm, when he was the ppt to go into a cave for several months with no clocks or light,
- He believed the date to be a month earlier than it was.
-This suggests that his 24-hour sleep-wake cycle was increased by the lack of external cues, making him believe one day was longer than it was, so his circadian rhythm had changed to more hours than 24 because there was no light to reset it

Question 16

what is an issue with Siffre’s research

Answer 16

Siffre’s research is criticised do to it being a case study where he was the only ppt.
This caan’t be generalised to a wider population due to the lack of it’s sample size, implying it lacks population validity

Question 17

what research supports Siffre’s findings

Answer 17

Siffre’s findings in the cave has been supported by Aschoff and Weber- conducted in a bunker where they only had artificial light, which they could turn on and off when they wanted
Aschoff and Weber found that the ppts in the bunker settled into a longer sleep wake cycle of between 25-27 hours

Question 18

Evaluating endo and exo on the sleep wake cycle
para 2
research support for e…..genous …………. on the sleep wake cycle conducted by M……. studying on ha……

Answer 18

research support for endogenous pacemakers on the sleep wake cycle conducted by Morgan, who bred abnormal hamsters to have a circadian rhythm of 20 hours and not 24.
The SCN neurons in these hamsters where transplanted into normal hamsters, and they subsequently displayed the same abnormal 20 hours, showing the SCN had an imposed it’s pattern onto the hamsters.
However, difficult to generalise findings on hamsters to humans which reduces the validity of the study.
Although is demonstrates the SCN being an endogenous pacemaker and it’s impact on biological rhythms such as sleep wake cycle, it does’nt provide evidence for these cycles in humans.

Question 19

Evaluating endo and exo on the sleep wake cycle
para 3
limitation
argued to be reductionist due to it being o…………… a complex human phenomena

Answer 19

Argued to be Reductionist due to it being oversimplifying a complex human phenomena.
for example, the cycle is influenced by social norms and people, as it has become socially acceptable to do daily routines in the day and not at night.
Therefore, research discussed before has been criticised for not considering a range of factors.

Question 20

Evaluating endo and exo on the sleep wake cycle
para 4
research implying that artificial light can act an an exogenous zeitgeber, so it doesn’t have to be natural light
research by V…..er et al 201.

Answer 20

Futhermore, there’s research implying that artificial light can act an an exogenous zeitgeber, so it doesn’t have to be natural light.
research by Vetter et al 2011
used 2 volunteer ppts over 5 weeks, and found that when there was warm artificial light, they had the normal circadian rhythm. But the other group under blue enriched light had synchronised their rhythms to office hours.
This confirms that light is a dominant exogenous zeitgeber for the SCN, which is effective depending on its spectral composition.

Question 21

evaluation on supporting indiv differences in circadian rhythms
Duf… et al 200.
‘morn…… people’ prefer to r…… and g. to bed _am and __ pm
‘ev……. people’ prefer to w….. and g. to bed l…. __am and _ am.
demonstrates their may be in…… differences that researchers should f….. on in their research

Answer 21

However, noticing Individual differences when investigating circadian cycles.
e.g. Duffy et al. (2001) found that ‘morning people’ prefer to rise and go to bed early (about 6 am and 10 pm)
whereas ‘evening people’ prefer to wake and go to bed later (about 10 am and 1 am).
This demonstrates that there may be INNATE individual differences in circadian rhythms, which suggests that researchers should focus on these differences during investigations.

Question 22

research into the disruption of biological rhythms
para 1
case study Sif… is subject to cri……
res……. … and lack of g……….
but research supporting his findings by A…….. and W ……

para 2
research is diff…. to g………. as its use of ham……..
by m…………

para 3
redu………….
study by Ve…..
this reduces validity of other study
as…… and w…..

Answer 22

Siffre’s case study has been criticised because he was the sole researcher and ppt. This leads to potential researcher bias and it also lacks generalisability to a wider population.
Research supports his findings is Aschcoff and Weber- bunker- artifical light - 25-27 hours

para 2
Morgan - hamsters- SCN - demonstrates how endogenous pacemakers can disrupt biological rhythms in humans

para 3 reductionist
vetter - artificial light does impact
warm light - normal hours
enriched blue- office
this reduces the validity of Aschpff and Weber who studied impact of natural light - shows it was not a holistic study as it didnt consider artificial, or diet, temp, stress