Biological Rhythms: Circadian rhythms RWA – real world application

Aims To know the biological clock in control of the

Circadian RhythmTo understand the difference between Endogeous

Pacemakers and Exogenous ZeitgebersTo be able to evaluate the RWA application of circadian

rhythms research

Key concepts RWA – Real world application

• Animal research justification • Chronobiology• Economical gains • Chronotherapy • Chronotherapeutics • Photo-therapy • Melatonin treatment

IDEAs

Disadvantages of the Biological approach

•The Synoptic Tool Kit

• (Synoptic - presenting a summary or general view of a whole)

•The Synoptic Tool Kit

• (Synoptic - presenting a summary or general view of a whole)

Biorhythms

• A biological rhythm is any change in a biological activity that repeats periodically. Often synchronised: Daily, Monthly and annual.

Circadian = 24 hour cycle; S/W cycle Infradian = 24+ hour cycle; Menstrual cycle Ultradian = <24 hours; Sleep

Biological rhythms

• Circadian = 24 hour cycle; S/W cycle • Infradian = 24+ hour cycle; Menstrual cycle • Ultradian = <24 hours; Sleep

Costs Benefits

Justifying animal research using the CBA - Cost benefit analysis• Making decisions

based on a CBA: – Quality of research– BUAV campaigns

against Vivisection studies

– Benefits to humankind

– Suffering to animals

– Can we generalise

• Making decisions based on a CBA – cost benefits analysis: – Quality of research– BUAV campaigns

against Vivisection studies

– Benefits to humankind

– Suffering to animals

– Can we generalise

Writing commentary for RWA and ethics • Research into circadian rhythms have huge real world

application. • A common criticism of animal research is the

unethical suffering caused by vivisection studies. • For example, .... deCoursey/ralph/morgan .....• However, A cost benefit analysis would suggest that

the research is justifiable. • For example, the exxon valdez/chernobyl disasters ..

Occurred when people should have been sleeping. Therefore this research must be completed to alleviate human suffering.

Patricia DeCoursey (2000) • She removed/damaged the SCN

in 30 chipmunks. The chipmunks were returned to their natural habitat.

• After 80 days, significantly more of the SCN-lesioned chipmunks had been killed by weasels.

• This was presumably because these chipmunks remained awake in their burrows and the weasels could hear the noise and were able to locate the chipmunks.

IDEA: Cruel, Unethical, costs benefits analysis, generalisable, extrapolation, Rights, Speciesism, Equality, Respect,

BUAV, Home office license, 3RRR’s

IDEA: Cruel, Unethical, costsbenefits analysis,

generalisable, extrapolation,Rights, Speciesism, Equality,Respect, BUAV, Home office

license, 3RRR’s

Morgan (1995) Hamster research• He gave hamsters brain transplants of SCN

from a mutant strain (which he bred) whose biological rhythms have a shorter cycle.

• The recipients adopted the same activity cycles as the mutant strain.

• The finding that animals transplanted with the SCN adopts the same activity patterns as their donors, along with the fact that the circadian rhythm cannot be manipulated beyond certain limits, suggests that bodily rhythms are primarily endogenous.

IDEA

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, Ralph (1990) Hamster study

• Aim: To show that the SCN generates the circadian rhythm in mammals.

• Sample: hamsters, with a genetic abnormality affecting their circadian cycle that resulted in a 20-hour circadian cycle, rather than a 24-hour one.

• Method: Their SCNs were removed and placed in the brains of a group of hamsters with a normal 24-hour cycle.

• Result: The experimental group shifted to a 20-hour cycle.

• Conclusion: the hamsters’ circadian cycle was regulated by the SCN. When normal hamsters were given an abnormal SCN they developed an abnormal circadian cycle.

Ralph (1990) also transplanted an SCN from a free running (25 hour) hamster into the mutants; who adopted a 25 hour rhythm. The mutant gene was tau which caused the 20 hour cycle. Showing how genes affect behaviour.

Animal Research

• Groblewski et al (1980) Rat study • Ralph (1990) mutant hamsters (mutant SCN

from foetuses into adults) and also a transplant from a free running (25 hour) hamster into a mutants adopted a new 25 hour rhythm.

• The mutant gene was tau which caused the 20 hour cycle. Showing how genes affect behaviour.

Justification of animal research: Working when we should be sleeping!

Human error and shift work • Negative effects of sleep deprivation

– e.g. decreased attention– slowing of reasoning skills– impaired reaction could have serious consequences on the ability to

do work or drive safely.

Possible justification for animal researchPractical application of Psychology in the real world

RWA

Chrono-biologists

Economic gains

• Shift work costs– Fatigue – Illness

• Costs the economy $77 billion – So does this

research have RWA?

– Any implications?

Chronotherapy

• This is where if you are an owl/lark and out of synchronisation with the outside world. Your sleep patterns can be manipulated and rotated, by sleeping earlier/later so that you will eventually be in line with the average sleep wake cycle. Thus leading to synchronised sleep wake activity.

This has RWA to teenagers and students who have Circadian phase disorders. For example, Owls who have circadian phase disorder – DSPS.

Chronotherapeutics

The symptoms of many illnesses fluctuate over the 24hr cycle, such as hay fever, and are worst around dawn; heart attacks are likely to happen in the morning when blood is more prone to clotting (thickened blood).

Aspirin can be used to treat heart attacks. This is most effective around 11.00 pm which allows time for the aspirin to peak in the blood (it takes 2-4 hours). Does this research have RWA? What are the implications?

Phototherapy - Czeisler et al (1990) • Czeisler et al (1990) believes that shift work environments that are warm and dimly

lit are counter productive. So, they compared the rate of adaptation of two groups of ppts to an imposed shift change by asking them to report to the laboratory during the night and sleep at home during the day. – The control group worked during the night in ordinary indoor lights of about 150 lux. – The experimental group worked under bright illumination of 7000-12000 lux, equivalent

to early morning light. – The experimental group were also asked to stay in complete darkness from 9am to

5pm, whilst the controls were given no specific instructions. • The resetting of the biological clocks were monitored by measuring body

temperature, which varies rhythmically. – After 6 days the experimental group had all shifted the low point of the circadian

temperature rhythm by 10 hours, – the controls 1 hour. – Bright lighting in the work place seems to be key to helping workers to adapt to new

shifts so that they are alert at work and sleep well during the day. Even in this situation adaptation can take up to 4 days, so workers who change shift every week would spend most of their time desynchronised .

Phototherapy leading to SCN circadian adjustment : Dawson and Campbell

• It might help if shift workers reset their biological clocks as quickly as possible. Bright lights as a substitute to daylight has proven effective in resetting the biological clock. 7000 lux – 12000 lux (Czeilser 1990)

• Dawson and Campbell exposed workers to a 4 hour pulse of very bright light which appeared to help them work better and more productively. (link to$77 billion dollar costs in US)

Melatonin treatments for Jet Lag and Shift Work

Melatonin Melatonin helps Jet/Shift lag because it binds to neurone receptor sites on the SCN, altering their activity, resetting the biological clock.Takahashi (2002) found that Melatonin speeds up the resynchronisation process after an 11 hour flight. Sharkey (2001) Melatonin speeds up biological adjustment to shift patterns, and increased sleep time during non-work periods.Herxheimer and Petrie (2001) reviewed 10 studies and found that where melatonin was taken near to bedtime, it was remarkably effective. However, if taken at the wrong time of day it may actually delay adaptation

.