Biopsychology-biological rhythms

Question 1

what is a circadian rhytms

Answer 1

Circadian rhythms are cycles that have a 24 hour periodicity meaning that they have a cycle length of about 24 hours

Question 2

give 2 examples of circadian rhythems

Answer 2

-sleep/wake cycle
-core body temperature

Question 3

describe out core body temperature

Answer 3

it is at its lowest (about 36˚C) at about 4:30 am and at its highest (about 38˚C) at about 6pm. Evidence suggests that body temperature may influence our mental capabilities. The warmer we are internally, the better our cognitive performance.

Question 4

what is our circadian rythems driven by

Answer 4

Our circadian rhythms are driven by our internal body clock known as endogenous pacemakers.

Question 5

How does our endogenous pacemakers work to help us go to sleep

Answer 5

1. light enters the eye and is focussed into the retina which contain special light detecting ganglion cells.
2. Ganglion cells detect how bright the light is and send this information along the optic nerve to the SCN
3. as light levels decrease the SCN sends a signal to the pinneal gland which releases melatonin and causes you to fall asleep

Question 6

name the 2 endogenous pacemakers in your body

Answer 6

The pineal gland and the SCN function jointly as endogenous pacemakers in the brain

Question 7

what is an exogenous zeitgeber

Answer 7

The environmental cues such as light or temperature that can affect biological rhythms are called ‘exogenous zeitgebers’

Question 8

what are the 2 types of exogenous zeitgebers

Answer 8

light
social cues

Question 9

describe light as an exogenous zeitgeber

Answer 9

light can reset the body’s main pacemaker, the SCN.
· Light resets the internal biological clock each day, keeping it on a 24-hour cycle.

Question 10

describe social stimuli as an exogenous zeitgeber

Answer 10

Social stimuli, such as mealtimes and social activities, may also have a role as zeitgebers.

We eat meals at socially determined mealtimes, and go to bed and wake up at times designated as appropriate for our age, and so on.

· Our daily rhythms appeared to be entrained by social convention

Question 11

what is some supporting evidence for the use of social cues for exogenous zeitgebers

Answer 11

Aschoff et al (1971) showed that individuals like those who are cortically blind (totally blind) can compensate for the absence of zeitgebers such as natural light by responding to social zeitgebers instead.

Question 12

what is some supporting evidence for the use of exogenous zeitgebers and endogenous pacemakers in helping us entrain out biological rythems.

Answer 12

Siffre (1975) studied his own free running circadian rhythms by spending extended periods of time in caves, with no natural light or cues as to the day or time. He spent six months in a cave in Texas, he had artificial light to help navigate his way around the cave. His internal body clock was allowed to free run, and it settled into a sleep/wake cycle of around 24-25 hours. He resurfaced on the 17th September believing the date was 20th August.

shows us that EP and EZ work together to entrain us ad help us keep us in tune with our environement

Question 13

what is some supporting evidence to suggest exogenous zeitgebers are important

Answer 13

Skene and Arendt (2007) claimed that the majority of blind people who still have some light perception have normal circadian rhythms whereas those without any light perception show abnormal circadian rhythms. This demonstrates the importance of exogenous zeitgebers as a biological mechanism and their impact on biological circadian rhythms

Question 14

what is some supporting evidence to suggest that we have strong endogenous pacemakers

Answer 14

Morgan (1995) bred a strain of hamsters so that they had abnormal circadian rhythms of 20 hours rather than 24 hours. SCN neurons from these abnormal hamsters were then transplanted into the brains of normal hamsters. These normal hamsters then displayed the same abnormal circadian rhythm of 20 hours, showing that the transplanted SCN had imposed its pattern onto the recipients’ brains

-shows we have different internal body clocks
-cant extrapolate and generalise to humans

Question 15

what are some debates regarding EP and EZ

Answer 15

Despite all the research support for the role of endogenous pacemakers and exogenous zeitgebers, the argument could still be considered biologically reductionist. For example, the behaviourist approach would suggest that bodily rhythms are influenced by other people and social norms, i.e. sleep occurs when it is dark because that is the social norm and it wouldn’t be socially acceptable for a person to conduct their daily routines during the night. The research discussed here could be criticised for being reductionist as it only considers a singular biological mechanism and fails to consider the other widely divergent viewpoints.

Question 16

what are some other practical applications for reasearch into circadian rythems for shift work

Answer 16

One real world application of research into circadian rhythms is that it provides an understanding of the adverse consequences that occur when they are disrupted.
This has led to research into improving the effects of shift work (reducing accidents and improving productivity- economic benefits).
Gronfier found the use of pulses of bright light helped to entrain circadian rhythms and therefore avoid longer periods of desynchronisation.

Question 17

what are some other practical applications for reasearch into circadian rythems for administering drugs

Answer 17

pharmacokinetics. By understanding circadian rhythms and their impact on health, it can help determine the best time to administer drug treatments. For example, the risk of heart attacks is greatest in the early morning, so drugs can be taken at night

Question 18

what is infradian rhythems

Answer 18

Infradian rhythms last more than 24 hours.

Question 19

what is an example of infradian rhythem

Answer 19

An example is the menstrual cycle, which is dictated by the endocrine system.
However, this rhythm is not imposed purely by the release of hormones. It is suggested that zeitgebers such as light and odour are also involve

Question 20

what is supporting evidence for entrainment in a infradian rhythem

Answer 20

Stern & McClintock (1998) studied 29 women with a history of irregular periods. Samples of pheromones were gathered from nine women at different stages of their menstrual cycles, via a cotton pad placed in their armpit. The pads were treated with alcohol and frozen, to be rubbed on the upper lip of the other participants. On day one, pads from the start of the menstrual cycle were applied to all 20 women, on day two they were all given a pad from the second day of the cycle and so on.

Stern & McClintock found that 68% of women experienced changes to their cycle which brough them closer to the cycle of their ‘odour donor’.

entrainment occured our external environment impacts out internal environment

Question 21

supporting evidence for exogenous zeitgebers eg-light influencing infradian rhythms

Answer 21

Reinberg investigated a woman spending three months in a cave with only a small lamp as a source of light. As a result, her menstrual cycle shortened to 25.7 days (as appose to 28 days), showing that the level of light in the cave affected the woman’s menstrual cycle and how infradian biological rhythms can be influenced by external zeitgebers such as light.

Question 22

criticisms of supporting evidence for infradian rhythems

Answer 22

Early research studies of infradian rhythms suffered from an important flaw. It has been argued that many factors may affect the change of a women’s menstrual cycle that might act as confounding variables. E.g., stress, diet, exercise, this may explain why other studies (e.g., Trevathan et al. 1993) have failed to replicate the findings.

· Also, many of the studies have small samples of women reporting relying on self-report of the onset of their own cycle.

Question 23

alternative explanations for infradian rhyems

Answer 23

The effects of hormones can help explain menstrual synchronicity, whereby groups of women who live together, such as nuns, have menstrual cycles that become synchronised. The idea of communication via pheromones can neatly explain this idea as there must be something in the shared environment that acts as a zeitgeber

Theres an evolutionary adantage for this as it allows child rearing to occur at the same time which is more advantageous for survival
It is an outdated view of survival.

Question 24

applications of research into infradian rhythms.

Answer 24

Research into other infradian rhythms have shown that light therapy is one of the most effective treatments for seasonal affective disorder (SAD). Sanassi (2014) found light therapy reduced the effects of SAD in about 80% of people.
LINK TO ECONOMY

Question 25

what is an ultradian rhythms

Answer 25

Ultradian rhythms have a periodicity of less than 24 hours, meaning that more than one cycle occurs within 24 hours.

Question 26

give an example of ultradian rhythems

Answer 26

stages of sleep and BRAC
whole cycle takes 90m
we can have 4 stages of sleep in one night

Question 27

what is BRAC

Answer 27

Kleitman (1969) referred to the 90-minute cycle found during sleep as the Basic Rest Activity Cycle (BRAC).

However, Kleitman also suggested that this 90-minute ultradian rhythm continues during the day, rather than moving through sleep stages, we move progressively from a state of alertness to psychological fatigue approximately every 90 minutes.

For example, the familiar 10:30 am coffee break allows workers to divide the 9am to noon morning session into two 90-minute phases. This pattern is repeated in the afternoon, with cat-naps more likely in the mid-afternoon.

Question 28

what is some supporting evidence for ultradian rhythm

Answer 28

Ericsson et al (2006) studied a group of elite violinists and found that, among this group, practice sessions were usually limited to no more than 90 minutes at a time. Consistent with Kleitman’s claim that fatigue was a characteristic of the end of the BRAC cycle, Ericsson’s analysis also indicated that the violinists frequently napped to recover from practice, with the very best violinist’s napping more than their teacher’s nap. Ericsson discovered the same pattern among other musicians, athletes, chess players and writers.

suggest behaviour is cyclical

Question 29

more supporting evidence for ultradian rhythms

Answer 29

Dement & Kleitman (1957) monitored sleep patterns of 9 adults in a sleep lab. Brainwave activity was recorded on an EEG and the researchers controlled for the effects of caffeine and alcohol. REM activity during sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were, and participants woken during dreaming reported very accurate dreams.

suggest behaviour is cyclical

Question 30

strengths of research into ultradian rhythms

Answer 30

One strength of research into ultradian rhythms is that it has improved understanding of age-related changes in sleep. Sleep scientists have observed that SWS (slow-wake sleep) reduces with age. Growth hormone is mostly produced during SWS therefore this is reduced in older people.

According to Eve van Cauter et al. (2000), the resulting sleep deficit may explain various issues in old age, such as reduced alertness. This suggests that knowledge of ultradian rhythms has practical value.

Question 31

debates regarding ultradian ryhthems

Answer 31

Differences in the sleep patterns of individuals are usually attributed to differences in non-biological factors (e.g. room temperature, noise). However, a study by Tucker et al (2007) suggests that these differences are in large part biological and may even be genetic in origin. Pts were studied over 11 days and nights in a strictly controlled laboratory environment. The researchers assessed sleep duration, time to fall asleep and the amount of time in each sleep stage. They found large individual differences in each of these characteristics, which showed up consistently across the eight nights. For deep sleep (stages 3 and 4), the individual differences were particularly significant.

lab-lacks ecological validity