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biological rhythms - Coggle Diagram
biological rhythms
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Depressive disorder diagnosed by DSM-5 which has seasonal patterns of onset. SAD is a particular type of infradian rhythm called a circannual rhythm as it is subject to a yearly cycle. (NOTE: can also be classed as a circadian rhythm as SAD may be due to the disruption of the sleep wake cycle with prolonged periods of darkness during winter).
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o During the night (until dawn when there is an increase in light) the pineal gland secretes melatonin.
o During winter the lack of light in the morning means increased production of melatonin (the process continues until light). This is thought to impact the production of serotonin in the brain. Serotonin is linked to the onset of depressive symptoms.
Circadian Rhythms
Biological Rhythms: Patterns of changes in body activity conforming to cyclical time periods, influenced by both internal body clocks (endogenous pacemakers) and external environmental changes (exogenous zeitgebers).
Circadian Rhythm: A type of biological rhythm lasting around 24 hours, regulating various bodily processes such as the sleep/wake cycle and temperature fluctuations.
The Sleep/Wake Cycle:
The influence of daylight, a crucial exogenous zeitgeber, on the sleep/wake cycle is evident as people typically feel drowsy at night and alert during the day. However, investigations into what happens when the biological clock becomes free running and how it operates without external influence have been conducted.
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Despite lacking exposure to natural light (he had a lamp) and sound, Siffre maintained a regular sleep/wake schedule.
His experiments revealed that his biological rhythm extended slightly beyond 24 hours (around 25 hours), indicating the influence of exogenous zeitgebers on entraining the cycle.
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Poor Control in Studies: Despite participants' deprivation of natural light, access to artificial light could still affect their biological rhythms, serving as a confounding variable.
Individual Differences: Variability in individual sleep/wake cycles, preferences (e.g., early birds vs. night owls), and age-related changes pose challenges for research into the sleep/wake cycle, complicating generalizations. For example, siffre observes at the age of 60 his internal body clock ticked much more slowly than when he was a young man. This shows that even with the same person there are factors that prevent general conclusions being drawn.
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Practical Application to Shift Work: Disruption of circadian rhythms, as seen in shift work (night shifts) can lead to reduced concentration and increased health risks, highlighting the economic implications of managing worker productivity. Shift workers are 3 times more likely to develop heart disease which may be due to stress of aducsting to a different sleep wake cycle then leading to poor-quality sleep.
Practical Application to Drug Treatments: Understanding circadian rhythms informs the optimal timing of drug administration for various medications, enhancing their effectiveness. Fror example taking aspirin before bed can lower your chances of having a heart attack or stroke.
Understanding circadian rhythms is critical for optimizing various aspects of human health and performance. However, the complexity of these rhythms, coupled with individual differences and methodological limitations, underscores the need for careful consideration in research and practical applications.