circadian rhythms

• P: Hughes tested the circadian hormone release in four participants stationed at the british antarctic station

  E: at the end of the antarctic summer, cortisol levels followed the familiar pattern, reaching their highest point as the participants woke, and their lowest point as the participant went to bed. after 3 months of continuous darkness this pattern had changed, peak levels of cortisol now being at noon rather than as the men woke

  L: this suggests that the extremes of daylight found in polar regions of the world may be responsible for variations in circadian hormone release.
• P: research suggests there are individual differences in circadian rhythms

  E: one is cycle length, research has found that circadian cycles can vary from 13 to 65 hours. the other type of individual difference relates to cycle onset - individuals appear to be innately different in terms of when their circadian rhythms reach their peak

  L: this would explain why some people prefer to rise early and go to bed early, whereas others prefer to wake and go to bed later
• P: one real world application of circadian rhythms is chronotherapeutics - the study of how timing affects drug treatments

  E: the specific time patients take their medication is important as it can have significant impact on treatment success. its essential that the right concentration of a drug is released in the target area of the body at the time the drug is most needed.
• link for chronotherapeutics

  L: as a result, chronotherapeutic medications have been developed with a novel drug delivery system. these medications can be administered before the person goes to sleep at 10pm, but the actual drug is not released until the vulnerable period of 6am to noon.