Biological rhythms: Circadian Rhythms Flashcards
Biological Rhythms
Distinct patterns of changes in body activity that conform to cyclical time periods. They can be influenced by internal body clocks or external changes to the environment
Circadian rhythms
Biological rhythms, subject to a 24-hour cycle, which regulate a number of body processes such as the sleep/wake cycle and changes in core body temperature
What are biological rhythms governed by
Internal biological clocks - endogenous pacemakers
External changes in the environment - exogenous zeitgebers
How long does a circadian rhythm last?
24 hours
How is the sleep-wake cycle governed by both internal and external mechanisms
Exogenous zeitgebers: feel drowsy during the night and alert during the day shows the effect of daylight
Endogenous pacemakers: Rhythm governed by the suprachiasmatic nucleus
What did Siffre demonstrate about circadian rhythms
Spent long periods in dark caves to examine effects of free-running biological rhythms. In each study, his rhythm settled at 25 hours
What did Aschoff and Weaver find about circadian rhythms
Group of ppts spent 4 weeks in a bunker. All but one showed a sleep-wake cycle of 24/25 hours. Suggests natural cycle is slightly longer than 24 hours
What did Folkard et al’s study involve
Studied a group of 12 people living in a cave for 3 weeks. Gradually sped up clock, so the day only lasted 22 hours. Only one participant adjusted to the new regime. Suggests endogenous pacemakers have a stronger influence
How can research be applied to drug treatments?
Circadian rhythms coordinate the body’s basic processes. Implications for pharmokinetics. Research shows there are times of the day when drugs are more effective. Real-life medical benefits
Why is the use of small samples a limitation?
Participants may not be representative of the wider population limiting generalisations. Siffre observed differences as he grew older. Factors preventing conclusions being drawn.
Why is there poor control in research studies?
Ppts deprived of natural light still had access to artificial light as it was assumed this had no effect on rhythms. Czeisler was able to adjust ppts sleep wake cycle using artificial light. Ignored important confounding variable.
