Ultradian and Infradian

Question 1

What are ultradian rhythms?

Answer 1

Bodily cycles than span for less than a day

Question 2

What is the main example of an ultradian rhythm?

Answer 2

Sleep cycles, undergone daily when people sleep

Question 3

How long does the sleep cycles last for?

Answer 3

90 minutes, moving through 5 different stages

Question 4

How does the sleep cycle stages begin?

Answer 4

When the person is awake and displays Beta waves on an EEG machine

Question 5

What is displayed as the person starts to relax?

Answer 5

Alpha waves, as they are in calm-wakefulness

Question 6

What happens in stages 1 and 2?

Answer 6

Light sleep, displaying theta waves

Question 7

What happens in stage 2 regarding stimuli?

Answer 7

Although asleep, the person can still respond to external stimuli and so are easily woken

Question 8

What happens in Stage 3 & 4?

Answer 8

Slow Wave Sleep, where sleep is increasingly deeper and people are more difficult to wake.

Question 9

What happens in SWS?

Answer 9

Repair work takes place such as the production of growth hormones, cell growth and protein synthesis
-Sleep walking and night terrors may occur

Question 10

What is the final stage of sleep?

Answer 10

REM, where brain waves mimic those of the awake brain. Associated with dreaming, body is paralysed so only the eyes can move.

Question 11

As the night progresses, how do the sleep cycles change?

Answer 11

More REM and less time in other stages

Question 12

A criticism of research into sleep stages is that it is assumed when an individual is in REM, they are dreaming…

Answer 12

• One study, participants woken mid REM

- Many reported dreams, but dreams occurred outside of REM and some were not dreaming in REM

Question 13

What is a problem with the assumption that dreaming only and always occurs in REM?

Answer 13

• Link provides underlying support for theories like that of the theory dreams are a psychological read out of REM electric signals
• Theories rely on accuracy of link

Question 14

A strength of research into sleep cycles is that it was conducted in a lab experiment…

Answer 14

• strict control of variables such as light
• EEG machine: empirical data that can be analysed objectively
• Increases reliability

Question 15

Alternatively, the nature of such studies as lab experiments may limit the research…

Answer 15

• Lab setting is artificial and not representative of natural sleeping environments
• Quality/quantity of sleep affected, skewing results
• Lacks ecological validity and generalisability

Question 16

How long do infradian rhythms last for?

Answer 16

More than 24 hours but less than one year

Question 17

What is a main example of an infradian rhythm?

Answer 17

Menstrual cycle

Question 18

What role does I rhythm play in the menstrual cycle?

Answer 18

• Regulates oestrogen and progesterone secretion
• Stimulate release of egg and growth of lining of womb
• When unfertilised, bleeding for 3-7 days

Question 19

What is a lesser known I monthly cycle?

Answer 19

• Male monthly rhythm

- 49 to 102 days, variation of both body temperature and morning altertness

Question 20

Both the menstrual and male monthly rhythm thought to be controlled internally, with the hypothalamus acting as the endogenous pacemaker, but…

Answer 20

Evidence has shown exogenous zeitgebers to play a role too

Question 21

A limitation of research into the menstrual cycle is the assumption that they are controlled solely by a persons internal biology…

Answer 21

• Underarm sweat from donor women applied to the upper lips of female participants
• Despite pairs never meeting, menstrual cycles became synchronised
• Pheromones in sweat can influence the menstrual cycle

Question 22

Research into the menstrual cycle is determinist, why?

Answer 22

Because it is widely described as an endogenous rhythm

Question 23

What is an example of the determinism behind the menstrual cycle?

Answer 23

• PMS, psychological and physical symptoms

- Mrs English, a PMS sufferer drove her car into her married lover following an argument

Question 24

What happened to Mrs English?

Answer 24

• Charged with murder
• Decided she would be placed on probation instead on grounds of PMS
• Argument backed up by doctor

Question 25

In relation to Mrs English, what does this deterministic explanation assume?

Answer 25

• PMS is beyond the control of women, meaning they cannot be held liable for their actions

Question 26

On the other hand, evidence has been found to contrast the belief that bodily rhythms are beyond our control…

Answer 26

Stress hormone ACTH (helps waking up process) found in people told to wake up earlier than usual - cycle is not entirely biologically determined and can be influenced by our own free will

Question 27

What is another example of an Infradian Rhythm?

Answer 27

SAD, a depressive cycle taking place over a few months

Question 28

What happens to a SAD sufferer?

Answer 28

• Severely depressed in Winter months (cold and dark)
• Recover in Summer (light and warm)
• Less sunlight leads to more melatonin production which decreases serotonin, linked with depression and other mental disorders

Question 29

However, SAD may be a disrupted circadian rhythm rather than the outcome of an infradian rhythm…

Answer 29

• Routine change in Winter, people may go to bed earlier but get up at same time
• Gives impression to bio system of time shifting, a feeling like jet lag
• Not entirely biological as can be affected by external factors

Question 30

What is one application of research into SAD?

Answer 30

• Phototherapy
• Strong artificial lights (10k+ LUX) to alter melatonin and serotonin levels
• Daily use reported to ease depression and lethargy

Question 31

However, why has phototherapy been criticised?

Answer 31

• Placebo effect, although placebo was less effective, 32% did show some improvement from a placebo
• Partially psychological rather than biological determined??