Lesson 11 - Circadian Rhythms

Question 1

24-Hour Circadian Rhythms

Answer 1

The body-clock which is rest by levels of light.

Question 2

How Do Circadian Rhythms Work?

Answer 2

They’re driven by SCN - this pacemaker resets and must reset so it’s in sync with the outside world. Natural light helps reset this through photo entrainment. Light sensitive cells act as brightness detectors sending messages about the environmental light to the SCN which then co-ordinates the circadian system.

Question 3

SCN

Answer 3

Suprachiasmatic Nucleus

Question 4

Sleep Wake Cycle

Answer 4

Light and dark are the external cues telling us when to sleep/wake up. This rhythm dips and rises to make the strongest sleep between 2-4am and 1-3pm

Question 5

Homeostatic Control

Answer 5

This also controls the sleep/wake cycle - when we’ve been awake for a while homeostasis tells us when we need sleep as our energy will be depleted.

Question 6

Difference Between Homeostatic Control And Circadian Rhythms

Answer 6

Circadian rhythm keeps us awake at light and slept at dark whilst homeostatic control makes us sleepier as time goes on and energy goes lower regardless of light.

Question 7

Core Body Temperature

Answer 7

Michael Siffre - Core body tends to its lowest around 4:30am and highest at 6am. Sleep occurs at the decline of body temp and the increase makes ou feel alert in the morning.

Question 8

Core Body Temp Study

Answer 8

Folkard Et Al found children who heard stories at 3pm had better recall than those who heard it at 9am, meaning increased body temperature gives increased recall.

Question 9

Hormone Production

Answer 9

Michael Siffre - Hormone release follows a circadian rhythm - the release of melatonin from the pineal gland at it’s peak during daylight hours. By activating chemical receptors melatonin encourages sleep and its levels dip towards wake up time.

Question 10

Strengths

Answer 10

Practical Application

Question 11

Practical Application (+)

Answer 11

In chronotherapeutics it’s important to take medication at the correct time e.g. heart attacks are more likely in the morning so medication given at night and releases at 6am.

Question 12

Chronotherapeutics

Answer 12

The study of timing on drug medication.

Question 13

More Practical Application (+)

Answer 13

The effects of shift work - night shifts caused reduced concentration at 6am where mistakes are most likely, therefore companies can make work les busy at tis time.

Question 14

Weaknesses

Answer 14

Sample sizes
Artificial Light

Question 15

Sample Sizes (-)

Answer 15

Michael Siffre used small sample sizes making it less easily to generalise e.g. individual differences Amy have affected the results.

Question 16

Artificial Light (-)

Answer 16

In most studies participants were deprived of light and clocks but not artificial light which can control their sleeping pattern and in this day and age make circadian rhythms pointless.