circadian rhythms-use psychboost Flashcards
introduction
• Cyclical changes in the way that biological systems behave.
• Evolution - the environment has cyclical changes
• Circadian rhythms - 24 Hours cycle
• Optimises physiology and behaviour - day / night cycle.
• Tells our bodies when to sleep, rise, eat—regulating many physiological processes
nature of circadian rhythms
• Driven by body clocks - in all cells of our body
Synchronised by SCN (superchiasmatic nucleus)- in the hypothalamus
nature of circadian rhythms
• Driven by body clocks - in all cells of our body
Synchronised by SCN (superchiasmatic nucleus)- in the hypothalamus
• The pacemaker must be constantly reset to be kept in synch.
Light.
• Light sensitive cells in the eye send info about the environment to the SCN.
sleep-wake cycle
• Light and darkness are the external signals that determine when we should sleep/wake.
• Circadian rhythms also dip and rise at different times.
• Sleep and wakefulness are also under homeostatic control.(If you have been awake for long period of time, homeostasis tells you need for sleep is increasing because of how much energy you’ve been using whilst awake- homeostatic need for sleep increases gradually throughout day and reaches maximum in evening-been awake the longest and used up most energy.
-circadian system and homeostatic system affect the sleep-wake cycle.
-major alterations in sleep and wake schedules (eg jet lag) cause the biological clock to be out of balance.
strength-real world application
One real-world application of circadian rhythm research is chronotherapeutics - the study of how timing affects drug treatments.
The specific time that patients take their medication is very important as it can have a significant impact on treatment success. It is essential that the right concentration of a drug is released in the target area of the body at the time that the drug is most needed.
For example, the risk of heart attacks is greatest during the early morning hours after waking up.
Therefore chronotherapeutic medications have been developed with a novel drug delivery system.
These medications can be administered before the person goes to sleep at 10pm, but the actual drug is not released until the vulnerable period of 6am to noon (Evans and Marain, 1996)
This shows that research into circadian rhythms has not just furthered our understanding of the human body, but research applications have led to to the improvement of treatment for patients with a variety of conditions requiring drug therapy.
strength-case study evidence
Evidence for a free-running circadian rhythm comes from a series of study conducted by French cave explorer, Michel Siffre.
On several occasions Siffre has subjected himself to long periods of time living underground in order to study his own circadian rhythms.
While living underground he had no external cues to guide his rhythms - no daylight, no clocks or radio. He simply woke, ate and slept when he felt it was appropriate to do so. The only thing influencing his behaviour was his internal body clock i.e. his free-running body clock.
In several of his studies Siffre spent several months underground and every time his natural circadian rhythm to between 24-25 hours, which provides support for free-running circadian rhythms.
weakness-case studies and small samples
A limitation of research into the sleep/wake cycle is the tendency to involve small groups of participants or single individuals e.g. Siffre.
The people may not be representative of the wider population and this limits the extend to which meaningful generalisations can be made.
In his most recent cave experience Siffre (1999) observed, at the age of 60, that his internal clock ticked much more slowly than when he was a young man.
This illustrates the fact that even when the same person is involved, there are factors that vary which may prevent general conclusions being drawn.
