circadian rhythms

• Circadian rhythms are driven by out body clocks found in every cell of out body. These are driven by the suprachiasmatic nucleus (SCN). Light sets the body clock to the right time from light sensitive cells in the eyes working with the SCN. Circadian rhythms are those which last 24 hours, for example the sleep wake cycle.
• . The circadian rhythm determines when we should sleep and when we should be awake. It rises and dips throughout the day, strongest sleep drive is usually between 2-4am and 1-3pm (post lunch dip). If we haven’t had much sleep (sleep deprived), these dips are usually more intense.
• Sleep and wake cycle are also under the influence of homeostatic control. When we have been awake for a long period of time, homeostasis tells us the need for sleep is increasing due to the amount of energy used up. Usually builds up in the day reaching the max at night when you sleep. The internal circadian clock is ‘free running’ and will continue even if there are no cues. This cycle is intolerant to any chances as it will throw it all off balance (jet lag).
• Other circadian rhythms include core body temperature and hormones. The lowest out temperature reaches is at around 4.30am and highest around 6pm. The changes in temperature occur in the normal circadian rhythm as sleep occurs when temperatures begin to drop and rise in the last few hours promoting wakefulness. A small drop also occurs around 2-4 which is why people may feel tired in the afternoon. Hormone production can be included in circadian rhythms as, when it gets dark and time to sleep, Melatonin will be released and stopped in the morning before the person wakes.

   
• Research suggests that there is individual differences in circadian rhythms.

  Research has found that cycle length can vary from 16-35 hours. There is also evidence of differences in cycle onset. Individuals have been found to be different in when they reach their peak. This would explain why some people tend to sleep early and wake up early, or sleep late and wake up late.

  Therefore, findings about circadian rhythms may not be fully generalisable as there can be some differences.
• A flaw has been discovered with research from cicardian rhythms.

  In most studies, the participants were isolated from variables that may affect their circadian rhythms, such as clocks, radios and daylight. However, they did have artificial light as they believed a dim artificial light would not affect their circadian rhythms. However, alternate research has shown that it can in fact alter circadian rhythms, as this was tested and proved.

  This suggests that some studies may have been affected by this variable and so reduces the internal validity.
• A strength of this research is the application to drug treatments.

  The specific time that a patient takes their medication is very important as it can have a significant impact on treatment success. The drug is needed to be released at the time it is mst needed. For example, the risk of heart attacks is much greater in the morning.

  As a result, drugs have been developed that can be taken at night and not released until early in the morning.
• A weakness is that some have found that temperature may be more important than light in controlling the body clock.

  Although light may be the trigger, SCN transforms the light signals into neural messages that set the bodys temperature. Body temp fluctuates in the 24 hour period, and even a slight change in temperature can send poweful signals to the bodys body clocks. The fluctuations in temp set the timing of cells in the body and causes tissues/organs to become active or inactive.

  This suggests that temperature may be more important compared to light.