A weakness into research of circadian rhythms is that it can be argued they lack internal validity. Another example of a circadian rhythm is the core body temperature cycle, which is lowest at around 4: Moreover,RVE8-LNKs interaction enables a permissive histone-methylation pattern H3K4me3 to be modified and the histone-modification itself parallels the oscillation of clock gene expression.
From this case study we can conclude that endogenous pacemakers and exogenous zeitgebers need to interact to be synchronised. But there are times when people having the same age and gender may still have different sleeping duration needs.
Sleep and Circadian Rhythms, retrieved April 12, from http: Szymanski showed that animals are capable of maintaining hour activity patterns in the absence of external cues such as light and changes in temperature.
The researchers speculate that these two rodents notice that the apparent distance between the sun and the horizon is shortest once a day, and, thus, a sufficient signal to entrain adjust by. The rhythms are entrainable. The use of rats provided a stepping stone towards developing a hypothesis for humans.
As a result, the findings do not reflect true isolation and have lower internal validity, so his rhythm may not have adjusted so well if he had been truly isolated. Morgan investigated the role of endogenous pacemakers, in particular the SCN, in the circadian rhythm belonging to hamsters.
The idea that core body temperature effects cognitive ability is supported by Gupta who found that performance on an IQ test was best at 7pm compared to 9am and 2pm, a factor that should be taken into consideration when taking exams. However, there is also evidence that the circadian rhythm can be altered by external environmental cues, called exogenous zeitgebers, for instance- light.
Popper believed that observations should be collected from which a hypothesis can be formulated and tested under controlled conditions. This would suggest that the use of artificial light may have effected the internal validity of the study.
Morgan removed the SCN in hamsters…. The highly controlled experiment means that the study is easily replicable.
They agreed to wake up at 7: Under normal conditions our sleep-waking cycles and our body temperature cycles are synchronised, we go to sleep when temperature is falling and wake up when temperature is rising. This unusual setting means that the study lacks mundane realism and the results may not be applicable to real life situations.
This therefore exhibits a limited and unrealistic projection of human behaviors because in the real world both nature and nurture interact with one another. Their interactions result in an interlocked feedback loop of gene products resulting in periodic fluctuations that the cells of the body interpret as a specific time of the day.
These may interface with endocrine glands of the brain to result in periodic release of hormones. The psychologists assume that the damage to the SCN is the only causation of the disturbed sleep there is no consideration that the sleep-waking cycle could be a more complex mechanism.
Clock genes are discovered from Drosophila, and they act together with the clock neurones. There are two unique rhythms, one during the process of hatching called eclosion from the pupa, and the other during mating.
Conversely, too much light shuts off the production of melatonin. In the study by Folkard et al, one person did manage to maintain a hour circadian rhythm, which shows other factors can override the internal clock.
This therefore exhibits a limited and unrealistic projection of human behaviors because in the real world both nature and nurture interact with one another.
Phytochromes B—E are more stable with phyB, the main phytochrome in seedlings grown in the light. They found that the free running cycle persisted with a sleep wake cycle of 25 hours, sometimes increasing to Outline and evaluate research into circadian rhythms (8+16 marks) Describe and evaluate research into infradian rhythms (8+16 marks) Discuss research into ultradian rhythms (8+16 marks) Outline and evaluate research into circadian rhythms (8+16 marks) AO1 – Endogenous pacemaker.
Describe circadian rhythms (8marks) Circadian rhythms occur every 24 hours; an example of a circadian rhythm is the sleep-waking cycle. We are diurnal animals who are active during the daytime and asleep at night, other animals are nocturnal they are active at night but asleep during the day.
Describe and Evaluate Research on Circadian Rhythms With Reference to Endogenous Pacemakers and Exogenous Zeitgebers - Download as Word Doc .doc.
Describe and evaluate research into circadian rhythms (24 marks) Circadian rhythms are biological cycles that last around 24 hours such as the sleep-wake cycle.
It is suggested that this circadian rhythm is free running and controlled by endogenous pacemakers (internal body clock). Describe and evaluate research into circadian rhythms (8+16) Research into circadian rhythms has assessed the effects of isolating participants from external time cues (exogenous zeitgebers) on our 24 hour cycles, and suggesting that an internal body clock (endogenous pacemaker) creates a free running sleep/wake cycle rhythm of 25 hours.
Describe and Evaluate Circadian Rhythms Describe circadian rhythms (8marks) Circadian rhythms occur every 24 hours; an example of a circadian rhythm is the sleep-waking cycle. We are diurnal animals who are active during the daytime and asleep at night, other animals are nocturnal they are active at night but asleep during the day.Download