Alternative transcript:

intense when we are sleep deprived -disrupted by major changes in sleep schedules e.g., jet travel or shift work What did he do? he isolated himself from all daylight by spending 6 months in a dark cave, with only artificial light to help him navigate within the cave -one of the best indicators of the circadian rhythm. -It is at its lowest (about 36 degrees) at about 4.30 am and its highest at about 6 pm. OUTLINE OF RESEARCH INTO THE SLEEP-WAKE CYCLE CONDUCTED BY SIFFRE, 1975 What did he find? -During the normal circadian rhythm, sleep occurs when the core temperature begins to drop, and body temperature begins to rise during the last hours of sleep, promoting a feeling of alertness in the morning. 2 His internal body clock was allowed to 'free-run' and at first, it was erratic. However, it eventually settled into a sleep/wake cycle of 25-30 hours continued to fall asleep and wake up on a regular schedule Why does this research support the view that human behaviour is affected by circadian rhythms? This is a strength of the endogenous pacemaker theory because his results suggest that in the absence of exogenous zeitgebers such as natural light sources, circadian rhythms are roughly maintained which supports the existence of an internal body clock. EVALUATION OF RESEARCH INTO CIRCADIAN RHYTHMS (THE SLEEP-WAKE CYCLE) +/- Supported by CASE STUDY research: + Practical application: P Siffre's research supports the claim that humans have a circadian rhythm that lasts approximately 24 hours and is governed by an endogenous pacemaker. E Siffre found that, when he isolated himself from all daylight and his internal body clock was allowed to 'free-run', it eventually settled into a sleep/wake cycle of 25-30 hours. E This is a strength of the endogenous pacemaker theory because his results suggest that in the absence of exogenous zeitgebers such as natural light sources, circadian rhythms are roughly maintained which supports the existence of an internal body clock however this is limited due to the fact he was the sole participant in this study ergo the results are limited as they may not be representative of the general population moreover Siffre had taken in an artificial lamp which may have acted as an exogenous zeitgeber meaning his results may not be as valid as originally thought limiting the support onto humans containing circadian rhythms. Overall there is no reason Siffre is not a normal member of the human race ergo his findings may apply to others, also it is extremely difficult to test the effects of endogenous and exogenous ergo the results may not prove much however they do strongly suggest the theory is correct. - Affected by artificial light: INFRADIAN RHYTHMS Seasonal affective disorder (SAD) a depressive disorder which has a seasonal pattern of onset and is described and diagnosed as a mental disorder in DSM-5. main symptoms of SAD are persistent low mood alongside a general lack of activity and interest in life. - Individual differences: 3 Menstruation The menstrual cycle has a duration of more than 24 hours and this can vary between 23 days and 36 days, but averages 28 days regulated by hormones and ovulation takes place roughly halfway through the cycle main symptoms of SAD are persistent low mood alongside a general lack of activity and interest in life. OUTLINE OF RESEARCH INTO THE MENSTRUAL CYCLE CONDUCTED BY MCCLINTOCK & STERN, 1998 What did they do? What did they find? -29 women with a history of irregular periods -Samples of pheromones were gathered from 9 women at different stages of their menstrual cycles -given a new pad every day to supply the samples of pheromones Why does this research support the view that human behaviour is affected by infradian rhythms? As it provides clear evidence that a woman's menstrual cycle can be altered by communication with pheromones (exogenous factor), showing how exogenous factors and infradian rhythms can affect human behaviour EVALUATION OF RESEARCH INTO INFRADIAN RHYTHMS (THE MENSTRUAL CYCLE) - Small sample size of research in support: Methodological issues 68% of the women experienced changes to their cycle which brought them closer to the cycle of their 'odour donor'. P There are many factors which may affect women's menstrual cycles including stress, diet, and exercise. E These might act as confounding variables which means that the pattern of synchronisation observed by McClintock & Stern may be no more than would be expected to occur by chance. E This 4 With a sample size of only 29 women, ergo the population validity of this sample is limited their conclusion that a woman's menstrual cycle can be altered by communication with pheromones (exogenous factors) may be invalid since their sample may be unrepresentative of a wider population. However, there is no evidence that this is, in fact, the case. As means that their conclusion that a woman's menstrual cycle can be altered by communication with pheromones (exogenous factors) may be invalid +practical application P One of the most effective treatments for SAD is phototherapy. E This is a lightbox which stimulates very strong light in the morning and evening. It is thought to reset melatonin levels in people with SAD and relieve symptoms in up to 60% of sufferers (Eastman et.al. 1998). E Although there remains some debate about phototherapy, its apparent success suggests that infradian rhythms are indeed affected by exogenous zeitgebers such as light. Stages 3 and 4: Known as deep sleep/ slow wave sleep Difficult to wake someone up Brain waves are slower than stages 1 and 2 Stage 5 such, it is reasonable to argue that the small sample size alone is not sufficient reason to discount the findings or conclusions of this research. Consisted of 5 stages Stages 1 and 2: Sometimes known as light sleep where an individual can be easily woken Brain wave patterns start to slow down - Individual differences: ULTRADIAN RHYTHMS The sleep cycle (stages of sleep) 5 REM sleep- rapid eye movement, to denote the fast jerky activity of eyes under the eyelids Body paralysed yet brain activity speeds up as if it's awake OUTLINE OF RESEARCH INTO THE SLEEP CYCLE CONDUCTED BY DEMENT & KLEITMAN, 1957 What did they do? What did they find? ● ● 9 participants- 7 males, 2 females asked to report to the laboratory at bedtime, connected to EEG caffeinated drinks were not permitted to be drunk before the time of sleep ● All participants had periods of rem sleep every night High incidences of dream recall when participants were awakened during rem periods of sleep Why does this research support the view that human behaviour is affected by ultradian rhythms? + Objective evidence in support: A strength of D and Ks research is that EEGs had been used which provides us with highly empirical data. This is useful as EEGS provide objective evidence showing that sleep follows a typical pattern throughout the night. This is a strength due to the fact these findings provide us with verifiable evidence for ultradian rhythms. If awakened during the other stages, low amounts of dreams were reported As the research used EEGs which provided us with objective evidence showing that sleep follows a typical pattern throughout the night, this suggests that human behaviour is affected by infradian Rhythms 6 EVALUATION OF RESEARCH INTO ULTRADIAN RHYTHMS (THE SLEEP CYCLE) - Small sample size of supporting evidence: A limitation of the research provides would be that it contains a small sample size meaning it may not be representative of the target population as it has low population validity. This is because the participants had been 9 in total, 7 males and 2 females, ergo their conclusion that the sleep follows a typical pattern throughout the night may be invalid due to their sample being unrepresentative of their target population, ergo may not apply to others. On the other hand, there is no evidence which suggests that the small sample size is not biologically determined: There Is evidence to suggest that sleep patterns may be biologically determined. For example, tucker et al discovered a large difference in the sleep patterns between individuals, this was controlled in a lab and was consistent over 11 nights. This suggests that sleep patterns may be partly determined by genes. However, this support may be limited due to possible extraneous variables e.g., the fact it had been undergone in a laboratory, for example, the behaviours of individuals' sleep may differ due to the settings in which they slept e.g., their bed and a laboratory ergo this research suffers from low ecological validity. Free 7 sufficient reason to discount ht findings or conclusions of the research. SUMMARY TABLE - CIRCADIAN, ULTRADIAN AND INFRADIAN RHYTHMS INCLUDING THE DIFFERENCES BETWEEN THEM BIOLOGICAL RHYTHM CIRCADIAN ULTRADIAN INFRADIAN LENGTH OF CYCLE EXAMPLE OF RHYTHM 8 SUPPORTING STUDY EVALUATION KEY PAST PAPER QUESTIONS – SEE ALSO STUDY GUIDE NOVEMBER 2020 Explain the difference between infradian rhythms and ultradian rhythms. [2 marks] SPECIMEN PAPER #3 The human female menstrual cycle is an example of one type of biological rhythm; it is called a: A circadian rhythm B infradian rhythm C ultradian rhythm [1 mark] PAST PAPER QUESTIONS 2021 & 2022 – IF APPLICABLE NOTES ON THE PAST PAPER QUESTIONS 9