• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14
  15. 15
    15
  16. 16
    16

Biological Rhythms

Extracts from this document...

Introduction

Biological Rhythms, Sleep and Dreaming a) Biological Rhythms A biological rhythm is a biologically driven behaviour that is periodically repeated. These rhythms are governed by both internal (endogenous) and external (exogenous factors). There are three types of biological rhythm. These are: Circadian, Infradian and Ultradian rhythms. Circadian Rhythm Circadian rhythms take place once every 24 hours. The Sleep-wake Cycle The best example of a circadian rhythm is the 24 hour sleep-wake cycle, associated with which are many cyclical changes with active and dormant periods, for example body temperature. Research has studied whether circadian rhythms are natural and triggered internally (endogenous) or whether they rely upon external cues in the environment (exogenous). Research has involved participants being deprived of possible zeitgebers (an external event that partially controls biological rhythms - literally means 'time-giver'), such as sunrise and sunset and temperature changes during a 24 period. Siffre (1972) was removed from the normal light-dark cycle, by being kept in a dark cave for 2 months. There were no zeitgebers such as natural light or sounds and he had no idea what time it was. He had food and drink and so on. His behaviour such as when he slept/woke and when he ate his meals was monitored. At first the findings showed there was no clear pattern in his sleep-waking cycle. However, later his sleep-waking cycle settled down to a regular pattern of about 25 hours i.e. longer the normal 24 hour cycle. This suggests that our internal biological clock must have a 25 to 30 hour cycle and that that our zeitgebers must reset the clock to our normal 24 hour day. This study is supported by and Wever (1979) who discussed studies on participants who spent several weeks or months in an underground bunker without any cues to light or dark. The findings showed that most of them displayed circadian rhythms of about 25 hours. However, this is not a universal finding. Folkard (1996) studied one individual who had a 30 hour cycle. ...read more.

Middle

Nevertheless, with this study it is difficult to separate the effects of sleep deprivation and the methods used to keep the animals asleep i.e. constant stress. However, there are inconsistencies in relation to the Restoration theory. We can argue that if sleep does have a restorative function we would expect that people who are more active would require more sleep. But we have seen the research evidence does not support this view i.e. Rosenzweig et al (1999). Furthermore, there is need for multi-perspective evidence that explains sleep as a psychological and physiological function. Also, the Restorative theory doesn't explain why there are so many differences in the way animals sleep. It may be that sleep serves an ecological function instead. Ecological theories Ecological theories take the view that sleep is an adaptive function. They presume that sleep occurs in all animals because it promotes survival and reproduction. Predator Avoidance Meddis (1975) proposed the predator avoidance theory which claims that the function of sleep is to keep animals inconspicuous and safe from predators at times of the day when there are most vulnerable. For most animals, this means sleeping during the hours of darkness. It follows that those species in danger from predators should sleep more of the time than those species that are predators. However, Allison and Cicchetti (1976) pointed out that in fact predators tend to sleep more than those preyed upon. This might seem inconsistent with ecological theories of sleep. However, species that are in danger from predators might benefit from remaining alert most of the time and sleeping relatively little. Interesting evidence which supports the claim that the pattern of sleep is often dictated by the environmental threats faced by animals was reported by Pillieri (1979). Dolphins living in the River Indus are in constant danger from debris floating down the river. As a consequence, these dolphins sleep for only a few seconds at a time to protect themselves from debris. ...read more.

Conclusion

Research Evidence Webb and Cartwright (1972) described a study which provides support for their theory, in which participants were given problems to solve and then allowed to go to sleep. Some were then woken when they entered REM sleep. They found those that had been allowed to sleep uninterrupted were able to provide more realistic solutions to the problems the next day, suggesting that there REM sleep had given them the opportunity to work through their problems. In another study Cartwright (1984) interviewed women who were undergoing divorce and were either depressed or not depressed. He then compared them with a non-depressed married group who has never considered divorce. All participants were studied over a 6 nights in a sleep laboratory. The non-depressed divorcing women reported having longer dreams which dealt with marital status issues. This apparently helped the individuals cope better. Such issues were absent from the dreams of the depressed groups. Presumably the depression was associated with an inability to deal with problems The above findings are supported by Hartmann (1973 who found that people who were experiencing various kinds of problems had more REM sleep than the less troubles individuals. Evaluation The problem solving theory seems to be a reasonable account of dreaming and is supported by some research studies. However, this approach doesn't explain why people and animals have dreams not related to the solution of problems. Also, the problem solving theory implies that it would be useful to remember our dreams. But, it seems puzzling that we forget about 95% of our dreams. There is also the question of why sleep is necessary because we can also solve problems by engaging in another task for a while, as indicated by the saying 'a change is as good as rest'. The most reasonable conclusion is that the problem solving theory helps to explain some dreams, but does not provide a comprehensive account of all dreams. Finally, this approach is uninformative about the physiological processes involved in dreaming. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Cognitive Psychology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Cognitive Psychology essays

  1. Memory and Mental Imagery

    This distracter task involved asking the participant to write the number '432' onto a plain piece of paper and then asking them to subtract three until they were told to stop. This distracter task took two minutes. Then they were asked to write as many words from their list as

  2. Describe the application of behaviorist perspectives in health and social care. Describe the application ...

    Understand this concept he links it to an iceberg. He said that out conscious mind was the tip of an iceberg and the remaining part of the iceberg was out unconscious side. This states that we are only are of a small percentage of our minds.

  1. Discuss biological and psychological explanations of depression

    For unipolar depression he found concordance rates of MZ= 40% and DZ= 11%. This was replicated by Bertelsen et al (1977) who also found similar concordance rates of (for unipolar disorder) MZ= 59% and DZ=30% and for bipolar disorder found rates of MZ= 80% and DZ= 16%.

  2. Summarise the aims and context of Bennett-Levy & Marteau (1984) Fear of animals: What ...

    The informal interviews indicated that tactile properties ('feel') of animals and the sounds they made were also important variables in evoking fear responses. Although participants were advised to view all the animals as harmless, the researchers found through informal follow-up questioning that this still had some effect on the ratings given.

  1. 'Biological explanations of schizophrenia tell us all we need to know about this disorder.(TM)

    who found in a set of quadruplet girls, all four girls developed schizophrenia, and although the age of onset slightly differed, it does offer strength to the idea of a genetic component. A problem presented with genetic evidence is that the concordance rates are not 100% and therefore this data does not exclude environmental input i.e.

  2. why do humans forget?

    Evidence AGAINST: 1. This theory can't explain why young people forget things, before their brain cells start decaying. 2. Tulving (1968) experiment showed that it is possible to forget information, but then remember it later. Trace decay theory can't explain it. 3. Older memories should be forgotten before newer memories, but why do

  1. Report on Psychological Research into Eyewitness Testimony

    As an anxiety provoking situation cannot be induced, only participants who are willing and who have already experienced a suitably traumatic event can be studied. The suggestion of repression featuring in eyewitness testimony is still significant though, as eyewitnesses are often trying to recall a particularly frightening event. Loftus (1979)

  2. Evaluate 3 Approaches to treating Mental Disorders: Psychodynamic, Biological and Behavioural Approach.

    Ideas put forward by Freud have greatly influenced the therapies used in treating mental illness, Freud was the first to recognise that psychological factors could be used to explain physical symptoms such as paralysis. Psychoanalysis has been widely used to help people overcome psychological problems.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work