circadian rhythms

Question 1

what is a biological rhythm

Answer 1

a change in body processes or behaviour in response to cyclical changes (works in cycles) within the environment.

Question 2

what is a circadian rhythm

Answer 2

a specific type of biological rhythm occurring across a 24 hour period.

Question 3

what are the other two circadian rhythms

Answer 3

• Core Body Temperature - is at its lowest at 4.30am (36’c) and highest at 6pm (38’c). As core body temperature rises in the morning this helps you feel more alert.
• Hormone Production - Hormone release follows a circadian rhythm. Melatonin is the “sleep” hormone which is at peak release during darkness

Question 4

what is the sleep-wake cycle

Answer 4

• During daylight hours we feel alert and when night falls we feel drowsy.
• Therefore the presence or absence of DAYLIGHT has a major influence on our biological rhythms (our sleep-wake cycle).
• The circadian rhythm also dips and rises at different points of the day, so our strongest desire to sleep occurs between 2-4am and 1-3pm (after lunch).
• The sleepiness we experience during these times is less intense if we have had sufficient sleep, but more intense if we are sleep deprived.
• Homeostasis also helps maintain the circadian rhythm.
• When energy levels run low after being awake a long time, our body gives us signals that we need to rest.
• This “homeostatic drive” increases throughout the day.
• Our circadian clock is “free-running”- it will maintain a 24-25 hour cycle even in the absence of external cues.
• any alterations to our body clock are extremely difficult to handle because they disrupt our bodily rhythms.
• So jet lag, shift work etc have a negative impact on our circadian rhythms.

Question 5

what is the role of the SCN + what does it stand for

Answer 5

• suprachiasmatic nucleus
• Our circadian rhythms are driven by our body clocks, found in all the cells of the body.
• They are synchronised by our master circadian pacemaker - the suprachiasmatic nucleus/nucleus (SCN), found in the hypothalamus.
• This pacemaker must be constantly reset so that our bodies are constantly in synch with the outside world.
• Light provides the primary input to this system, setting the body clock to the correct time.
• In mammals, light sensitive cells in the eye act as brightness detectors and send messages to the SCN to help regulate our circadian rhythms.

Question 6

what are the +ve AO3 points for circadian rhythms

Answer 6

• Siffre’s Cave Study
• Wever
• Folkard
• Practical application - shift work
• Practical application - drug treatment
• Real world application - iphones

Question 7

expand on the +ve AO3 point, Siffre’s Cave study

Answer 7

• Siffre spent several extended periods underground to study the effects of lack of external cues on his own biological rhythms.
• Siffre went underground in July 1962 and when he surfaced 8 weeks later in mid September he believed it was mid-August.
• His body clock always settled into a rhythm just over 24 hours (around 25) and he always fell asleep and woke up regularly.
• This study + Wever show that our natural circadian rhythm may be slightly over 24 hours and support that it is a hard-wired rhythm

Question 8

expand on the +ve AO3 point, Wever

Answer 8

• Convinced pps to spend 4 weeks in a WW2 bunker deprived of natural light.
• All but one of the pps had circadian rhythms of 24-25 hours.
• This study and Siffre show that our natural circadian rhythm may be slightly over 24 hours and support that it is a hard-wired rhythm.

Question 9

expand on the +ve AO3 point, Folkard

Answer 9

• Studied pps who lived in a dark cave for 3 weeks, rising at 7.45 am and going to bed at 11.45pm.
• The psychologists gradually sped up the clock so that a 24 hour day was reduced to 22 hours (pps deceived)
• Results were that the pps found it very difficult to adjust when they started messing with the cycle so this is further support for circadian rhythms being hard-wired (free-running) in us.

Question 10

expand on the +ve AO3 point, Practical application - shift work

Answer 10

• Psychologists’ work into circadian rhythms can be used to inform managers of shift-workers so that the negative impact of circadian rhythms on their work is minimised.
• Shift workers experience periods of seriously reduced productivity around 6am (where accidents are more likely) all due to their circadian rhythms being messed up.
• In this way, managers can minimise the negative impact of these rhythms and protect their employees and their business.
• this has implications for psych & the economy

Question 11

expand on the +ve AO3 point, Practical application - drug treatment

Answer 11

• Circadian rhythms have a huge impact on how well drug treatments can be absorbed and distributed around the body.
• Psychological research has enabled advice to be given to patients with a wide range of disorders about exactly when they should take medication to maximise its effectiveness.
• This also has implications for the economy.

Question 12

expand on the +ve AO3 point, Real world application - iphones

Answer 12

• Apple recently introduced the “Night Shift” mode on iphones because of research that shows your circadian rhythms are DISRUPTED by the artificial light omitted from mobile devices and tablets!
• It is important to note that all these studies were on NATURAL light but research now suggests that ARTIFICIAL LIGHT (which ALL pps had access to) effects Circadian Rhythms

Question 13

what is the -ve AO3 point for circadian rhythms

Answer 13

Application - Las Vegas
- The casino/hotels in Vegas use all this knowledge of Circadian rhythms to their MASSIVE advantage.
- There are no windows. No natural light. No clocks. Free drinks and food. Pumping in oxygen. Psychedelic carpets to keep you awake
- All for the purpose of DISRUPTING your rhythms and MAKING YOU SPEND MORE MONEY.