Biopsychology - Circadian Rhythms Flashcards
What are biological rhythms, and what influences them?
Biological rhythms are periodic physiological changes in living organisms, influenced by endogenous pacemakers (internal biological ‘clocks’) and exogenous zeitgebers (external environmental changes like light). Rhythms can occur multiple times a day (ultradian rhythms), last longer than a day (infradian rhythms), or follow a 24-hour cycle (circadian rhythms).
What are examples of circadian rhythms?
Two key examples of circadian rhythms are the sleep/wake cycle and core body temperature. Circadian rhythms repeat every 24 hours and are influenced by internal and external factors.
How does the sleep/wake cycle demonstrate circadian rhythms?
The sleep/wake cycle shows how light (an exogenous zeitgeber) affects drowsiness at night and alertness during the day. In the absence of external stimuli, such as light, researchers study whether this cycle remains free-running, maintaining a regular rhythm.
What did Siffre’s cave study reveal about the sleep/wake cycle?
Michel Siffre spent extended periods underground without natural light or sound. In his 1962 and 1970s studies, his free-running circadian rhythm settled at around 25 hours, slightly beyond the standard 24 hours, while he continued waking and sleeping on a regular schedule.
What findings came from other research into the sleep/wake cycle?
Jürgen Aschoff and Rütger Wever found that participants in a WWII bunker without natural light displayed free-running circadian rhythms between 24 and 25 hours. In another study, Folkard et al. gradually sped up a clock to a 22-hour day, and participants could not comfortably adjust, suggesting the cycle is influenced by internal factors that cannot easily override external cues.
What is one evaluation point about the practical applications of circadian rhythms?
Knowledge of circadian rhythms has practical applications for shift work. It shows that night workers are at a greater risk of reduced concentration at around 6 AM, leading to workplace accidents. Shift workers are also more likely to develop heart disease (Knutsson, 2003), highlighting the importance of understanding circadian rhythms to improve worker productivity and health.
What is one evaluation point ?
Circadian rhythms co-ordinate body processes, influencing drug absorption and effectiveness. Research into this has led to the development of guidelines for the timing of medication dosages, such as anti-cancer, cardiovascular, and anti-ulcer drugs (Baraldo, 2008).
What is one evaluation point?
Research like Siffre’s involves small sample sizes, limiting generalisability. Siffre’s internal clock ticked slower at age 60 compared to earlier studies, showing individual differences. Small samples may not represent the wider population accurately.
What is one evaluation point?
Studies in artificial conditions often fail to control for confounding variables. For example, participants in circadian studies could have access to artificial light, which can reset biological rhythms. This questions the validity of findings as it introduces uncontrolled external factors.
