Evaluations - A03

• Strength of circadian rhythm - practical applications eg chronotherapeutics. Research into circadian rhythm demonstrated that there are certain peak times during day or night when drugs likely to be most effective which is often based on body temperature and metabolism cycles. Led to development of guidelines in timings of drug dosing for whole range of medications including cardiovascular and respiratory which will help improve effectiveness of such medication. Thus, supports value of research into CR as applied to real life to help people and health.
• Strength of CR - Tucker studied ppts over 11 consecutive days & nights in controlled environment, assessed sleep duration, time to fall asleep and amount of time in each sleep stage. Found large individual differences in sleep duration, time to fall asleep and differences remain consistent over time period. Demonstrates differences between ppts not driven by external circumstances (lighting) as circumstances controlled, despite this sleep differences remained intact indicating internally, biologically controlled. Supports biologically controlled increasing validity.

  C - x ecological validity
• Strength of CR - Michael Siffre spent 7 months underground in cave. Adequately fed, had opportunities for exercise, able to make contact at all time by telephone but lacked any cues about time of day. Resurfaced in mid-September 1962 after spending 2 months in caves of southern alps believing to be mid-August. Sleep pattern settled down to 25 hours although he continued to fall asleep and wake up on regular schedule. Suggests existence of strong, free running CR which is internal biological rhythm and not easily affected by external environment.

  C - X had torchlight - extraneous variable
• Limitation of infradian rhythm - evidence to suggest exogenous zeitgebers affect IR. Russel found female menstrual cycles became synchronised with other females through body odour exposure. Sweat samples from one group of women rubbed onto upper lip of another group. Tho two groups kept separate, their menstrual cycles synchronised. Suggests synchronisation of menstrual cycles affected by pheromones which have effect of ppl nearby rather than person producing them. Findings indicate external factors taken into consideration when investigating IR and perhaps more holisistic approach taken.
• Limitation of infradian rhythm - relies on poor and unscientific evidence, menstrual synchronisation by Russel et al failed to take into account confounding variables which affect menstrual cycles such as stress, change in diet and exercise; weakens cause-effect between pheromones and menstrual synchronisation. + studies based on small samples of women lacking population validity and generalisability issues. Thus question validity of studies and be careful when inferring cause-effect.
• Strength of ultradian rhythm - research support, Dement & Kleitman monitored sleep patterns of nine adults in a lab using EEG while controlling for effects of caffeine and alcohol. Found that REM activity correlated with experience of dreaming and increased brain activity while sleeping. Ppts woken during dreaming reported very accurate recall of their dreams. Demonstrates REM sleep important part of ultradian sleep cycles and what they entail and represent is accurate. Supports claim made by research on ultradian dream cycle and supports value of REM sleep.
• Limitation of UR - study in controlled lab setting, differences in sleep patterns not attributed to situational factors but only to biological differences between ppts. Study provide support role of innate biological factors and UR, psychologists examine other situational factors may play role. Plus, way research conducted tell us little about UR in humans. When investigating sleep patterns, ppts subjected to specific level of control and attached monitors to measure rhythms. Invasive for ppts leading them to sleep not representative of ordinary sleep cycle. Thus lack ecological validity.