biospych - bio ryhthms

Question 1

what is an example of circadian rhythm

Answer 1

The sleep-wake cycle is an example of a circadian rhythm
Humans and animals will sleep or wake according to this cycle, dependent on the amount of light (an exogenous zeitgeber) they are exposed to

Question 2

what are external factors of sleep wake cycle called.

Answer 2

Endogenous zeitgebers are environmental events, like the changing of light, which reset the body clock

Question 3

what plays a role in sleep.

Answer 3

Melatonin plays a role in ‘triggering’ sleep by responding to a decrease in the levels of light
Shift work has been found to lead to desynchronisation of circadias rhythms and can lead to adverse cognitive and physiological effects

Question 4

what detects light in the brain.

Answer 4

The suprachiasmatic nuclei (SCN) in the hypothalamus detects the level of light present and then uses this information to coordinate the activity of the entire circadian system

Question 5

what is an example of adverse effects of dyssynchronisation of circadian rhythms.

Answer 5

For example, memory lapses or issues with fertility
Jet lag is another example that can lead to desynchronisation of circadian rhythms

Question 6

supporting research, what did Siffre (1973) do, and folklard et a;. (1980)

Answer 6

Supporting research:
Siffre (1973) – a case study in which Siffre spent two months in a cave deprived of light and sound, determining that his circadian rhythm remained between 24-25 hours

Folkard et al. (1980) implemented a 22-hour sleep-wake cycle and found that participants experienced problems with recall in their short-term memory
circadian-rhythms-determine-our-sleep-wake-cycle-2

Question 7

what is a critique of Siffres study.

Answer 7

Critique:
Case studies such as Siffre (1973) cannot be generalised beyond the single participant
Folkard et al.’s (1980) research lacks ecological validity due to its lab setting

Question 8

how does this link to Approaches:

Answer 8

This topic sits within the biological approach which assumes that human behaviour can be explained in terms of internal physiological functions such as the activation of the pineal gland in the sleep-wake cycle linked to hormones such as melatonin
However, human behaviour does not always fit neatly into a biological explanation, for example some people will not necessarily respond to a pre-determined sleep-wake cycle which means that the biological approach cannot always account for individual differences

Question 9

what are ultradian rhythms

Answer 9

Ultradian rhythms occur more than once within a 24-hour cycle, for

example, the cycles of sleep

There are five recognised stages of sleep
Stages 1 and 2 are the sleep escalator
Stages 3 and 4 consist of the delta waves of deep sleep
Stage 5 is REM sleep, the stage in which dreaming occurs according to research

Question 10

what are infradian rythms

Answer 10

Infradian rhythms have less than one cycle in 24 hours.

Examples of infradian rhythms are the menstrual cycle and seasonal affective disorder (SAD)
A typical menstrual cycle takes around 28 days to complete and is the result of a change in hormone levels including oestrogen
SAD is usually experienced during the darker months of winter when more melatonin is secreted which may result in higher levels of depression

Question 11

The stages of sleep: an example of an ultradian rhythm

Supporting research:

Answer 11

McLintock et al. (1998): Infradian rhythms – a longitudinal field study in which the menstrual cycles of women became synchronised after being exposed to a ‘donor’ pheromone which acted as an exogenous zeitgeber
Dement and Kleitman (1957): Ultradian rhythms – participants in a sleep lab were attached to an EEG monitor which showed that REM sleep was correlated with dreaming
6-4-1-a-participant-in-a-sleep-study

A participant in a sleep study

Mc Lintock et al.’s (1998) research was a field study which means that an array of extraneous variables
For example, diet, exercise, pollution, could have interfered with the findings
Dement and Kleitman carried out their research in the 1950s which means that it may lack temporal validity
Temporal validity is to what extent research study findings can be generalised and applied to a current time or situation
For example, the use of digital technology such as smartphones, which did not exist at the time of the research, may be interfering people’s ultradian rhythms
This means new research should be undertaken on this topic

Question 12

Link to Issues and Debates:

Answer 12

There may be ethical considerations involved in conducting research on infradian rhythms as seen in McLintock et al.’s study (1998): deliberately disturbing a woman’s natural menstrual cycle could have far-reaching effects (e.g. to her fertility, to her emotional state) which the researchers would not be able to predict

Question 13

Endogenous Pacemakers overview

Answer 13

The rhythms of our body are regulated by two key factors - endogenous pacemakers and exogenous zeitgebers
Endogenous pacemakers are the internal mechanisms which determine the biological rhythms of the body
For example, the circadian sleep cycle
They are known as the internal ‘body clocks’ but, they can be affected by the external environment

Question 14

what does the SCN do

Answer 14

The suprachiasmatic nucleus is a major factor in the sleep/wake cycle - it is the most important endogenous pacemaker
It is the body’s ‘home-made’ method for inducing sleep
Specific biological triggers are involved which result in someone falling asleep

Question 15

the four stages of sleep

Answer 15

THEY EYE DETECTS LOW LIGHT LEVELS

THIS INFORMATION IS THEN SENT TO THE SUPRACHIASMATIC. NUCLEUS

THE SCN THEN ALERTS THE PINEAL GLAND TO SECRETE MELATONIN I

MELATONIN LEVELS INCREASE WHICH INDUCES SLEEP

Question 16

what are Exogenous Zeitgebers

Answer 16

Exogenous zeitgebers are any factors in the sleep-wake cycle which act as external cues to either wakefulness or sleepiness

Answer 17

The body can be entrained so that its internal mechanisms are altered by these artificial external cues - exogenous zeitgebers
Going to bed with the light on or a digital device placed next to the bed may keep levels of light unnaturally high and thus impact negatively on sleep
Light is the main and most important exogenous zeitgeber

Question 18

two supporting studies of exogenous zeitgeibers

Answer 18

Supporting research:
Morgan (1995): removed the SCN of hamsters and found that their sleep-wake cycle disappeared but then re-appeared once fetal hamster SCN cells had been transplanted into their brains

Campbell and Murphy (1998): demonstrated that light (in the form of a torch) is a key exogenous zeitgeber, even when shone on the back of participants’ knees, as it disrupted their sleep cycles by up to three hours

Question 19

Critisms of Morgans 1995 study and Campbells and Murphys study.

Answer 19

The use of animals in research (see Morgan, 1995 above) could be argued to be unethical if the procedures involved cause physical and/or mental harm to the animal

The sample size used in Campbell and Murphy’s (1998) study was 15 which is too small to be able to generalise from, meaning that the results lack external validity

Question 20

how do endogenous zeitgebers link to approaches.

Answer 20

As well as being part of the Biological Approach exogenous zeitgebers also have relevance to the Behaviourist Approach as the inclusion of social cues as triggers in the sleep-wake cycle draws from schedules of reinforcement which is a feature of operant conditioning.

Question 21

Linking to issues and debates

Answer 21

The argument for endogenous pacemakers and exogenous zeitgebers as key players in the sleep-wake cycle is the emphasis on the role of light in the processes involved
However, some people are able to (and may frequently) fall asleep in bright light, during daylight hours, etc. which means that light may not be as important to the sleep-wake cycle as some researchers suggest
It may be overly reductionist to focus on a narrow range of explanations when considering something as complex and variable as the patterns and habits involved in the sleep-wake cycle