Biopsych: Circadian rhythms Flashcards
What’s a circadian rhythm?
A type of biological rhythm that lasts for 24 hours and changes body processes e.g., sleep/wake cycle and core body temperature.
Examples of circadian rhythms?
Sleep-wake cycle
What’s the sleep-wake cycle?
has a recurring pattern as it oscillates between wakefulness and sleep in a 24-hour clock. On a healthy sleep-wake rhythm, humans spend approx 8 hours sleeping and 16 hours awake. The role of the sleep-wake cycle is to regulate our sleep at night and keep us awake during the day. Our biological clocks are present in every cell, synchronised by the suprachiasmatic nucleus (SCN) which is located in the hypothalamus. Genes produce proteins that continuously increase throughout the night while we sleep but reduce during the day. These fluctuations activate the sleep-wake cycle.
What governs the SWC?
Exogenous Zeitgebers
Endogenous Pacemakers
What’s an Exogenous Zeitgebers?
external cues/changes that help regulate an organism’s biological rhythms —> in relation to the SWC we feel drowsy when it’s night time and alert during the day which demonstrates the effect of daylight.
What’s an Endogenous Pacemakers?
internal biological mechanisms that regulate an organism’s biological rhythms —> in relation to the SWC if the biological clock was left to its own devices without the influence of external stimuli such as light – free running.
Who conducted the supporting case study for circadian rhythms (SWC)
Siffre
What’s Siffre’s case study?
Spent long periods underground with no radio, clocks, etc. He simply woke, ate and slept when he felt like it. After his first underground stay of 61 days in the Southern Alps he resurfaced on 17th September thinking it was the 20th August. This provides evidence for the influence of endogenous pacemakers as the sleep-wake cycle remained irregular.
What are the 4 AO3 points for Circadian rhythms?
+Practical applications
-Research into circadian rhythms lacks reliability
-Research into circadian rhythms have low population validity
-methodology
(+AO3) What’s the practical applications for Circadian rhythms?
Helps understand negative consequences of disrupted circadian rhythms. Night workers experience a period of reduced concentration at 6am which causes mistakes. There’s also a relationship between shift work and heart disease. There’s economic implications – make conditions better for shift workers (healthier and more productive).
(-AO3) How does research into circadian rhythms lacks reliability?
Individual differences greatly impact biological rhythms. More recent studies show variation of cycles (between 13-65 hours). Some people have a natural preference for sleeping and waking late or the opposite. Age differences in sleep patterns and varies between people. This shows a lack of reliability.
(-AO3) How does research into circadian rhythms have low population validity?
Research involves a small group of ppts or single individuals. When something varies between individuals so much a small sample is unlikely to be representative and therefore, is difficult to generalise. Suggests there may be other influences than the free-running clock and environmental influences.
(-AO3) Why is the methodology a weakness?
Poor control over extraneous variables. Individuals still had access to artificial light (Siffre had a lamp). This was thought to not affect free-running rhythms but since proven that artificial light can reset ‘biological clocks.’ Extraneous variables such a slight reduces the internal validity of the research.
