Ultradian and Infradian rhythms

Starter: Activity: ABC

Exam focus Describe one ultradian rhythm (5)

Model Answer Responses to this short answer question were often disappointing. The focus needed to be on ultradian rhythms, but many students were diverted into describing the stages of REM and NREM sleep in far too much detail. For full marks the focus needed to be on the patterning of the stages and the fact that the ‘sleep staircase’ repeats throughout the night in a rhythmic pattern.

Model Answer An ultradian rhythm is one with a periodicity of less than 24 hours and the best example is the transition between SWS and REM during a nights sleep. Sleep has a 90 minute cycle and we have between four and six of these per night. We start in stage 1 sleep, which is very light and go deeper, through stages 2 and 3 until entering deep sleep in stage 4. This is also known as slow wave sleep as the brain waves have low frequency. We then go through stage 3 and 2 again before entering a stage of REM sleep. This lasts for around fifteen minutes and we are in a very deep sleep during this time. However our brain is as active as if we were awake. We then move back into stage 2 and the cycle begins again as we descend into stage 3 and back into stage 4

Research Dement and Kleitman (1957) Kleitman (1969) Ericsson (2006) In pairs, look over the pieces of research on your handout. What does the study suggest about circadian rhythms? Extension: What evaluation points can we draw from the research?

Evaluation Evidence supports the idea of distinct stages in sleep (continued) Process the results of the Dement & Kleitman study and describe one strength and one limitation of it. Replications of this investigation have noted similar findings, though the small size of the original sample has been criticised. Nevertheless, the study suggests that REM (dream) sleep is an important component of the ultradian sleep cycle.

Evaluation Method When investigating sleep patterns, participants must be subjected to a specific level of control and be attached to monitors that measure such rhythms. This may be invasive for the participant, leading them to sleep in a way that does not represent their ordinary sleep cycle. This makes investigating ultradian rhythms, such as the sleep cycle, extremely difficult as their lack of ecological validity could lead to false conclusions being drawn.

Infradian rhythms

Objectives To be able to… Describe what an infradian rhythm is and give examples. Describe and evaluate research into infradian rhythms Challenge Discuss practical applications of research into infradian rhythms

What do you know already? 2 1 3 Identify the rhythms. Write down what you might already know. Get student to come up the board one at a time and use the interactive whiteboard. Can the rest of them say whether the assumptions/annotations are true/false? Can we eliminate any myths?

Infradian rhythms A biological rhythm that has a periodicity of more than one day. Menstrual cycle Hibernation SAD Testosterone production in hamsters

Infradian & Ultradian Rhythms AO1 Menstrual Cycle – governed by monthly changes in hormone levels within females, which govern ovulation. Seasonal Affective Disorder (SAD) A depressive disorder with a pattern of onset that varies with the seasons. It is a mental illness according to DSM5. Sleep Cycle – 5 distinct stages of sleep that occurs 90 minutes and cycles throughout the course of the night. Each level is characterised by a different level of brain activity monitored with EEG.

Videos https://www.youtube.com/watch?v=ayzN5f3qN8g (Menstrual Cycle) https://www.youtube.com/watch?v=lld7lFZm-m0 (SAD) https://www.youtube.com/watch?v=kaoMD1XI5u8 (Sleep) https://www.youtube.com/watch?v=ffKcep4jnlM

Consolidation Complete the Using information sheets given to you. If you do a graph, ensure it has appropriately labelled scales and axis! Consolidation Complete the Using information sheets given to you. Make a representation of the following cycles The role of hormones in menstruation. The role of hormones and light in SAD. The types of waves in the sleep cycle. Consider: 1: The peaks and troughs 2: Patterns formed within the cycle. 3: Ensure you annotate it thoroughly to show what it represents. Challenge: Explain how you know whether each on is an infradian or ultradian rhythm.

Guess the rhythm Using your representations (place them around the room) Can you guess which represents which rhythm and why? Make your guess and explain…

Marketplace Place your representations on your desk. Visit each one and… Draw a quick sketch of each Annotate it accurately Explain why it’s either an infradian or ultradian rhythm

Infradian rhythms: The Menstrual Cycle September 18

Cycles

The menstrual cycle During each cycle rising levels of the hormone oestrogen cause the ovary to develop an egg and release it (ovulation). After ovulation the hormone progesterone help the womb lining to grow quicker, readying the body for pregnancy. If pregnancy does not occur, the egg is absorbed into the body; the womb lining comes away and leaves the body (menstrual flow)

Seasonal Affective Disorder (S.A.D.) Lack of daylight Increases melatonin Fatigue Disordered sleep patterns Risk of depression Treated with UV light and/or melatonin therapy. For more info follow the link: http://hcd2.bupa.co.uk/fact_sheets/htm Research has found that SAD can be treated with light therapy. What are the problems associated with research such as this?

Infradian rhythms: Seasonal Affective Disorder (SAD) The hormone melatonin is implicated in the cause of SAD. During the night, the pineal gland secretes melatonin until dawn when there is an increase in light. During the winter, the lack of light in the morning means this secretion process continues for longer. This is thought to have an effect on the production of serotonin in the brain, which is the neurotransmitter linked to the onset of depressive symptoms. September 18

September 18

SAD: Research Egrise et al (1986) found we have lower levels of serotonin during the winter months Norway with prolonged periods of winter darkness have higher frequency of SAD Magnusson and Stefansson (1993) did not find this pattern Terman (1988) found SAD 10% in northern USA and only 2% in Florida

AO3 Burger Factory (PEL) Cut out the different parts of the burgers. All together there are 6 evaluation points. Arrange them into top bun, meat and bottom bun and stick them down in the right order. Once they have been stuck down… Label them as strengths or limitations of either menstruation, SAD or the sleep cycle. 2) Try to write a contradictory ‘however’ argument in response to them. Try to do this for as many as you can! This should be a challenge

This supports the synchronicity of the menstrual cycle. AO3 – Cut & Stick Burgers Support from the synchronicity of the menstrual cycle comes from McClintock (1998) This supports the synchronicity of the menstrual cycle. McClintock’s study provides support for the evolutionary basis of menstruation. 29 women with a history of irregular periods gave samples of pheromones at different stages of their menstrual cycle. Pads were used to collect this from armpits. These were then rubbed onto the upper lips of the other participants. One day one pads from the start of the menstrual cycle were applied to all women etc… This suggests that no synchrony in menstrual cycles would have been more adaptive for survival and for passing on genes to offspring. Schank (2004) argues that if there were too many females cycling together within a social group, this would produce competition for the highest quality males, lowering the fitness of any potential offspring. 68% of women experienced changes to their cycle, suggesting that the menstrual cycle can be synchronised to that of other women and supporting the role of exogenous factors On the other hand, some argue that synchronised menstruation would have been more of a disadvantage to evolution. For example if our ancestors menstruated together it could have been an evolutionary advantage. New babies would have been part of a social group which cared for one another, enhancing survival.

AO3 – Cut & Stick Burgers This is a major strength as understanding of the role of melatonin has helped to produce therapies to aid suffering of many SAD patients. McClintock’s study could have been subject to confounding variables. There is evidence to support the separate distinct sleep stages. Dement & Kleitman monitored sleep patterns of 9 adult participants in a sleep lab. Brainwave activity was recorded on an EEG and they found that REM sleep was correlated with dreaming. For example phototherapy works by simulating a very strong light in the morning and evening. It resets melatonin levels and relieves symptoms in up to 60% of sufferers found by Eastman. Research into SAD has produced great practical applications for sufferers. For example, there could have been many exogenous factors which influenced the women’s menstrual cycles. For example, diet, stress and lifestyle choices. Similarly the study relied on women accurately reporting the onset and duration of their cycles. This is a major disadvantage of the research, implying that synchronisation only occurred by chance, rendering the result as not useful and invalid. This suggests that REM sleep is a distinct stage in which dreaming takes place.

This supports the synchronicity of the menstrual cycle. Answers Support from the synchronicity of the menstrual cycle comes from McClintock (1998) McClintock’s study could have been subject to confounding variables. McClintock’s study provides support for the evolutionary basis of menstruation. 29 women with a history of irregular periods gave samples of pheromones at different stages of their menstrual cycle. Pads were used to collect this from armpits. These were then rubbed onto the upper lips of the other participants. One day one pads from the start of the menstrual cycle were applied to all women etc… For example, there could have been many exogenous factors which influenced the women’s menstrual cycles. For example, diet, stress and lifestyle choices. Similarly the study relied on women accurately reporting the onset and duration of their cycles. For example if our ancestors menstruated together it could have been an evolutionary advantage. New babies would have been part of a social group which cared for one another, enhancing survival. This supports the synchronicity of the menstrual cycle. This is a major disadvantage of the research, implying that synchronisation only occurred by chance, rendering the result as not useful and invalid. 68% of women experienced changes to their cycle, suggesting that the menstrual cycle can be synchronised to that of other women and supporting the role of exogenous factors

Answers On the other hand, some argue that synchronised menstruation would have been more of a disadvantage to evolution. Research into SAD has produced great practical applications for sufferers. There is evidence to support the separate distinct sleep stages. For example phototherapy works by simulating a very strong light in the morning and evening. It resets melatonin levels and relieves symptoms in up to 60% of sufferers found by Eastman. Dement & Kleitman monitored sleep patterns of 9 adult participants in a sleep lab. Brainwave activity was recorded on an EEG and they found that REM sleep was correlated with dreaming. Schank (2004) argues that if there were too many females cycling together within a social group, this would produce competition for the highest quality males, lowering the fitness of any potential offspring. This suggests that no synchrony in menstrual cycles would have been more adaptive for survival and for passing on genes to offspring. This is a major strength as understanding of the role of melatonin has helped to produce therapies to aid suffering of many SAD patients. This suggests that REM sleep is a distinct stage in which dreaming takes place.

Exam focus: 4 marks A psychologist wanted to test the effects of biological rhythms on the ability to solve maths problems. She used random sampling to form two groups each of 20 students. She tested one group on one set of maths problems at 3 am in the morning. The other group were tested on another set of maths problems at 3 pm in the afternoon. She found that performance of the group tested at 3 pm was significantly better than the group tested at 3 am. When submitted for peer review the paper was rejected because of serious design problems. Explain one problem with the design of this study and suggest ways of dealing with this problem.

Mark Scheme •        Problem – random sampling; the 3 pm group might simply have been better at maths than the 3 am group. The solution would be a matched pairs (matched on maths ability) or repeated measures design. •        Problem – use of different maths tests, with no evidence that they were matched for difficulty. The solution would be to use the same set of maths problems if a matched pairs design was used. •        Individual differences due to independent groups design so use repeated measures but would need different but equivalent tests and counterbalancing. •        Other issues, such as individual differences in biological rhythms (‘owls’ versus ‘larks’) confounding results. Such answers should be marked on their merits – is the problem plausible and is the solution sensible?