biopsychology - circadian rhythms.

Question 1

What is meant by a biological rhythm?

Answer 1

Distinct patterns of changes in the body activity that conform to cyclical time periods which are influenced by internal body clocks (endogenous pacemakers) as well as external changes to the environment (exogenous zeitgebers).

Question 2

What are the different types of biological rhythms?

Answer 2

• circadian rhythms.
• infradian rhythms.
• ultradian rhythms.

Question 3

What is meant by a circadian rhythm?

Answer 3

A type of biological rhythms that operates along a 24-hour cycle which regulates several bodily processes such as the sleep/wake cycle and core body temperature.

Question 4

What is the function of circadian rhythms?

Answer 4

Optimises and organism’s physiology and behaviour in to best meet the demands of the day/night cycle.

Question 5

What is the nature of circadian rhythms?

Answer 5

• driven by body clocks in all cells of our body.
• synchronised by the SCN (suprachiasmatic nucleus) located in the hypothalamus.
• the pacemaker (the SCN) has to be reset in order to keep in sync.
  ↳ done through light as it sets the body clock to the correct time known as entrainment.

Question 6

What are circadian rhythms driven by?

Answer 6

Body clocks in all cells of our body.

Question 7

Where are circadian rhythms located?

Answer 7

Hypothalamus.

Question 8

What is meant by thesleep/wake cycle?

Answer 8

Dictates when humans and animals should be asleep and awake.

Question 9

What is the sleep/wake cycle governed by?

Answer 9

An internal endogenous pacemaker called the SCN.

Question 10

What external cues determine our sleep/wake cycle?

Answer 10

Lightness and darkness.

Question 11

What was the aim of siffre’s cave study?

Answer 11

Investigate the influence of the absence of external cues on the circadian rhythms.

Question 12

What was the procedure of siffre’s cave study?

Answer 12

1. subjected himself to long periods of time underground without any external cues.
2. woke up, ate and slept when he felt it was appropriate to do so.
3. internal body clock was the only thing influencing his behaviour.
4. resurfaced in mid-September but thought it was mid-august.

Question 13

What was the finding of siffre’s cave study?

Answer 13

His biological rhythms was 25 hours but he did continue to fall asleep and wake up on a regular schedule maintaining a regular sleep/wake pattern.

Question 14

What were the conclusions of siffre’s cave study?

Answer 14

• biological clock runs at a natural rate.
• circadian rhythms persist despite the absence of exogenous zeitgebers.
• need entrainment from exogenous zeitgebers in order to keep to a 24 hour cycle.

Question 15

What was the procedure of aschoff and wever’s experiment?

Answer 15

Group of participants spent 4 weeks in a WW2 bunker where they has no natural light.

Question 16

What was the finding of aschoff and wever’s experiment?

Answer 16

All but one participant displayed similar results to that of Siffre having a circadian rhythm of over 24 hours.

Question 17

What was the conclusion of aschoff and wever’s experiment?

Answer 17

Our natural sleep/wake cycle is entrained by exogenous zeitgebers associated with our 24-hour day.

Question 18

What was the procedure of folkard et al (1985) experiment?

Answer 18

1. 12 people agreed to stay in a cave across a 3 week period.
2. went to bed and woke at a set time shown by a clock.
3. researchers sped up the clock so the day only lasted 22 hours.

Question 19

What was the finding of folkard et al (1985) experiment?

Answer 19

Only one of participant was able to adjust to this.

Question 20

What was the conclusion of folkard et al (1985) experiment?

Answer 20

The free running biological clock is able to override some external changes in the environment.

Question 21

How is hormone production related to circadian rhythms?

Answer 21

• hormone release follows a circadian rhythm.
• production and release of melatonin form the pineal gland has peak levels during hours of darkness.
• chemical receptors activated in the brain which leads to melatonin encouraging you to sleep.
• when it is dark more melatonin is produced.
• when it is light production of melatonin drops and the person wakes.

Question 22

What are the strengths of circadian rhythms?

Answer 22

• provides an understanding of the adverse consequences that occur when they are disrupted (desynchronisation)
  ↳ research into circadian rhythms and the impact of shift work has many economic implications in terms of maintaining worker productivity and preventing accidents in the workplace.
• high external validity due to practical applications to drug treatments.

Question 23

What are the weaknesses of circadian rhythms?

Answer 23

• use of case studies and small samples in research
  ↳ lacks population validity preventing general conclusions to be drawn.
• poor control in studies
  ↳ results of the original studies may lack internal validity.

Question 24

How is core body temperature related to circadian rhythms?

Answer 24

• indicator if circadian rhythms.
• lowest (36 degrees) at 4.30 am and highest (38 degrees) around 6pm.
• can affect our mental abilities.
• the warner we are internally the better our cognitive performance.
• sleep typically occurs when it drops.
• rises towards end of sleep cycle promoting feelings of alertness first thing in the morning.
• improved performance on IQ tests when assessed at 7pm as opposed to 2pm and 9am (Gupta 1991).