Biopsychology- Bio Rhythms: Circadian Rhythms Flashcards
Biological rhythms -
Distinct patterns of changes in body activity that conform to cyclical time periods. Biological rhythms are influenced by internal body clocks (endogenous pacemakers) as well as external changes to the environment (exogenous zeitgebers).
Circadian rhythm -
A type of biological rhythm, subject to a 24-hour cycle, which regulates a number of body processes such as the sleep/wake cycle and changes in core body temperature.
What are biological rhythms?
Biological rhythms are cycles that affect the behavior of body systems in all living organisms, governed by endogenous pacemakers (internal biological clocks) and exogenous zeitgebers (external environmental changes).
What are the different types of biological rhythms?
Biological rhythms include ultradian rhythms (occur multiple times a day), infradian rhythms (take longer than a day), and circannual rhythms (last for a year).
What is a circadian rhythm?
A circadian rhythm is a biological rhythm that lasts approximately 24 hours, regulating cycles like the sleep/wake cycle and core body temperature.
How does daylight affect the sleep/wake cycle?
Daylight is an important exogenous zeitgeber that helps regulate the sleep/wake cycle, making us feel drowsy at night and alert during the day.
What happens if the biological clock is left without external cues?
Without external cues like light, the biological clock may continue its cycle but might extend slightly beyond 24 hours, as observed in studies where participants were isolated from natural light.
What did Siffre’s cave study reveal about the biological clock?
Siffre’s cave study showed that in isolation from natural light, his sleep/wake cycle extended to about 25 hours, demonstrating a natural cycle slightly longer than 24 hours but still regulated to some extent by environmental cues.
What did Aschoff and Wever’s study find about circadian rhythms?
Aschoff and Wever’s study found that when participants were isolated in a WWII bunker with no natural light, their sleep/wake cycles extended between 24 and 25 hours, similar to Siffre’s findings.
What was the result of the study by Simon Folkard et al. (1985)?
Simon Folkard et al. (1985) found that when participants lived in a dark cave and had their clock gradually shortened to 22 hours, only one participant was able to adapt, suggesting that the circadian rhythm is strong and not easily overridden by external cues.
What is the practical application of circadian rhythm research for shift work?
Research into circadian rhythms has helped understand how disrupted sleep/wake cycles, as seen in shift work, can lead to reduced concentration and higher chances of mistakes, accidents, and health issues like heart disease.
How does circadian rhythm research impact drug treatments?
Circadian rhythms influence pharmacokinetics, affecting how well drugs are absorbed and distributed in the body. This has led to guidelines for timing drug dosing to improve effectiveness, especially for medications like anti-cancer, cardiovascular, and anti-epileptic drugs.
What is a limitation of studies on circadian rhythms, like those by Siffre and Aschoff?
A limitation is the use of small sample sizes and case studies, which may not be representative of the general population, reducing the generalizability of the findings.
How can poor control in circadian rhythm studies affect results?
Studies often used artificial light, assuming it would not affect the free-running biological rhythm, but later research, such as by Charles Czeisler et al. (1999), showed that even dim artificial light can adjust circadian rhythms, making it a potential confounding variable.
Why are individual differences a problem in circadian rhythm research?
Individual differences, such as variations in natural sleep/wake cycles (ranging from 13 to 65 hours) and preferences for being a “lark” or “owl,” complicate generalizing results, as do age-related changes in sleep patterns.
