Explanations of Disorders of Sleep

Explanations of Disorders of Sleep
Click on the topic that you want to go to: Insomnia Sleepwalking Narcolepsy

Insomnia Click on the section you would like to go to:
Guidance on evaluating studies Factors influencing insomnia Guidance on IDA for primary insomnia Explanations of primary insomnia Guidance on IDA for secondary insomnia Eplanations of secondary insomnia General commentary on primary insomnia explanations Return to main menu

Insomnia Factors influencing insomnia
Click on the section you would like to go to: Age & gender Sleep apnoea

Return to insomnia menu
Factors influencing insomnia: Age & Gender: Older people & women are more likely to suffer from insomnia In older people, this may because of increasing physical problems such as arthritis or diabetes In women, the greater likelihood of insomnia may be due to hormonal fluctuations (e.g. The menopause) Return to insomnia menu Return to main menu Go to sleep apnoea

Watch someone experiencing sleep apnoea Return to insomnia menu
Factors influencing insomnia: Return to insomnia menu Sleep Apnoea: During a bout of apnoea, carbon dioxide builds up in the bloodstream to the point where it stimulates chemoreceptors (neurons that detect specific chemicals in the blood) These cause the sufferer to wake up gasping for breath. Return to main menu Go to age & gender This is because the pauses in breathing that characterise the condition may occur for up to 50 times an hour, thus having a major disruptive effect on sleep Occasional bouts of sleep apnoea are quite common, but in some it is a regular occurance. Sleep apnoea can also be considered an explanation of secondary insomnia

Sleep Apnoea Return to sleep apnoea Return to insomnia menu
Watch clip again Why do you think this condition is linked to insomnia?

Insomnia Explanations for Primary insomnia
Click on the topic you would like to go to: Hyperarousal Personality

Guidance on evaluating studies Return to insomnia menu
Explantions for Primary insomnia: Personality: Kales et al (1976) found that insomniacs were more likely to internalise psychological disturbance, rather than acting out problems or being aggressive The researchers proposed that internalisation leads to higher levels of emotional arousal and increased likelihood of feeling anxious, which is why it is a risk factor for insomnia How well does this research support the view that internalisation causes insomnia? Guidance on evaluating studies Return to insomnia menu Return to main menu Go to hyperarousal

Insomnia Explantions for Primary insomnia: Hyper-arousal:
It has been suggested that insomniacs experience a state of hyper-arousal. Click on the links below for more information. Select two studies out of the three given to put onto your worksheets Research into hyper-arousal Study 1 Research into hyper-arousal Study 2 Research into hyper-arousal Study 3 Return to insomnia menu Definition of hyper-arousal

Hyper-arousal definition Return to hyperarousal main page
A majority of patients with insomnia are chronically hyperaroused and, surprisingly, not only at night. This means, among other things, that their metabolism is faster than that of good sleepers, their body temperature is slightly higher, their brain waves are faster, and they are thinking and speaking fast, highly aroused, as if anxious Return to hyperarousal main page

Research into hyper-arousal Study 1
Vgontzas (2001) found that insomniacs have increased levels of adrenocorticotropic hormone (ACTH) and cortisol, both of which are associated with stress and arousal Return to hyperarousal main page Go to study 2 Go to study 3 Guidance on evaluating studies

Nofzinger et al (2004) found that the transition from being awake to being asleep is usually associated with a decrease in activity in the brain stem, thalamus and prefrontal cortex. Using PET scans, Nolfzinger et al showed that insomniacs experienced a smaller decline in such activity when going to sleep. In fact, they found elevated level of activity in the brains of insomniacs Return to hyperarousal main page Go to study 1 Go to study 3 Guidance on evaluating studies

Winkleman (2008) Insomnia may be caused by specific changes in brain chemistry. They found that people who had been suffering with insomnia for more than six months have reduced levels in their brain of the neurotransmitter GABA. This is known to reduce levels of activity in the brain. Therefore, reduced GABA would lead to an inability to ‘switch off’ at night. Return to hyperarousal main page Go to study 1 Go to study 2 Guidance on evaluating studies

Return to insomnia menu
Guidance on evaluating studies When evaluating studies of insomnia think about the following points: Return to insomnia menu Are there any problems with making generalisations from this study? What method is being used? Are there any problems with using this method? What are the positive points relating to the way the study was carried out? Are there any problems with attempting to establish a cause and effect relationship from this study? What conclusion is the study attempting to draw? Return to main menu Play slide again

The nature nurture debate Return to insomnia menu
Guidance on using IDA to evaluate theories of primary insomnia The nature nurture debate Reductionism Some of these explanations are reductionist Does the explanation fall on the nature or nurture side of the argument? Are there any consequences of this (socially sensitive)? Could we explain the insomnia using the other side of the argument? What does that mean? Why does it matter? What factors have not been taken into account? Return to insomnia menu Return to main menu

First watch a brief case study of secondary insomnia
Explanations for secondary insomnia First watch a brief case study of secondary insomnia Click on the topic you would like to go to: or Medical conditions Mental Health

Return to secondary insomnia Return to insomnia menu
Watch clip again What are the factors that seem to be responsible for this woman’s insomnia?

Insomnia Explanations for secondary insomnia
Medical conditions: A range of medical conditions have been shown to be associated with insomnia Research into medical conditions and insomnia Katz et al (2002) conducted a study involving 3,445 patients with a diagnosis of one or more of five chronic medical conditions, including hypertension, congestive heart failure. Responses to self-administered questionnaires showed that 50% of them reported syptoms indicative of insomnia, such as difficulty initiating and maintaining sleep. Insomnia was rated mild in 34% of the patients and severe in 16% Guidance on evaluating studies Return to insomnia menu Return to main menu Go to mental health

Insomnia Explanations for secondary insomnia Mental health:
There is evidence to suggest that insomnia is an additional symptom for many people suffering with mental health difficulties Add the details of the following pieces of research to you worksheets: Research into secondary insomnia Study 1 Research into secondary insomnia Study 2 Research into secondary insomnia Study 3 Return to insomnia menu

Return to insomnia menu Guidance on evaluating studies
Explanations for secondary insomnia Return to insomnia menu Mental health research study 1: Weiss et al (1962) Go to Research Study 2 What do you think Weiss found? Click on the button to find out: Results Percentage of people reporting sleep disturbance Go to Research Study 3 72% Guidance on evaluating studies 18% Control group Psychiatric patients

Explanations for secondary insomnia Mental health research study 2: Go to Research Study 1 Ohayon & Roth (2003) Interviewed 14,195 participants representative of the general populations of the UK, Italy, Portugal and Germany over the telephone about their psychiatric history and their sleep patterns Go to Research Study 3 What do you think they found? Click on the button to find out: Guidance on evaluating studies Results zzz People with insomnia were six times more likely to report a mental health problem, such as depression or anxiety, than people without insomnia

Explanations for secondary insomnia Mental health research study 3: Go to Research Study 1 Serretti et al (2003) Found that insomniacs and Depressives may have similar abnormalities in their biological clocks. Patients with depression who have been found to have an abnormality in the genes that govern circadian pacemakers are more likely to experience severe insomnia Go to Research Study 2 Guidance on evaluating studies Why does this study maybe challenge the view that insomnia is caused by secondary factors?

The nature nurture debate Return to insomnia menu
Guidance on using IDA to evaluate theories of secondary insomnia The nature nurture debate Approaches Which approaches are used in this explanation? Does the explanation fall on the nature or nurture side of the argument? Are there any consequences of this (socially sensitive)? Could we explain the insomnia using the other side of the argument? What might that lead to? Why does it matter? What factors may not been taken into account? Return to insomnia menu Return to main menu

Precipitating factors Return to insomnia menu
General commentary on explanations of primary insomnia: When discussing explanations of primary insomnia, we need to understand the interaction between predisposing, precipitating and perpetuating factors Click on the section you would like to go to: Predisposing factors Precipitating factors Perpetuating factors Return to insomnia menu

Insomnia Predisposing factors
These are factors that make it more likely that a person will develop insomnia and include having a genetic predisposition towards insomnia In a twin study, Watson et al (2006) found that 50% of the variance in the risk for insomnia could be attributed to genetic factors Guidance on evaluating studies Precipitating factors Perpetuating factors Return to insomnia menu

Precipitating factors Return to insomnia menu
It is unlikely that predisposing factors alone can explain chronic primary insomnia. It is likely that precipitating factors play a part These include factors such as environmental stressors or change, which may trigger insomnia in those who are vulnerable Which IDA point does this link to? Predisposing factors Perpetuating factors Return to insomnia menu

Insomnia Perpetuating factors Perpetuating factors are factors which maintain the insomnia even when the original causes have disappeared These include being tense about going to bed because of previous experience of insomnia, or simply the expectation that sleep will be difficult I’m not going to be able to get to sleep I’m going to feel lousy again tomorrow I don’t feel tired Maybe I should try counting sheep three one two Damn! Predisposing factors Precipitating factors Return to insomnia menu

Sleepwalking Click on the section you would like to go to:
Explanation of sleepwalking: incomplete arousal Guidance on evaluating studies of sleepwalking Explanation of sleepwalking: genetics Guidance on using IDA for sleepwalking Explanation of sleepwalking: stress-diathesis Return to main menu

Return to sleepwalking menu
Explanations: Incomplete arousal Sleepwalking is a disorder of arousal EEG recordings show a mixture of delta waves which are characteristic of SWS sleep, but also higher frequency beta waves which are characteristic of an awake state It looks as though sleepwalking occurs when the person is awakened, but the arousal of the brain is incomplete Click on the links to remind yourself what the different brain waves look like: Return to sleepwalking menu But why does this state of incomplete arousal occur? Stage 4 sleep Awake

Return to incomplete arousal
Go to stage 4 sleep Awake Awake High frequency, low amplitude waves A 1 2 3 4 R C

Return to incomplete arousal
Go to awake Stage 4 Stage 4 EEG recording consists purely of delta waves A 1 2 3 4 R C

Explanations: genetics There is some evidence to suggest that sleepwalking may be genetically transmitted Look at the pieces of evidence to support the genetic explanation and add the details to your worksheets: Return to sleepwalking menu study 1 Study 2 Study 3

Return to sleepwalking menu Guidance on evaluating studies
Explanations: genetics Return to sleepwalking menu Research study 1: Bakwin (1970) Go to Research Study 2 What do you think Bakwin found? Click on the button to find out: Results Concordance rate for sleepwalking Go to Research Study 3 Guidance on evaluating studies MZ twins (19 pairs) DZ twins (14 pairs)

Explanations: genetics Return to sleepwalking menu Research study 1: Bakwin (1970) Go to Research Study 2 What do you think Bakwin found? Click on the button to find out: Results Concordance rate for sleepwalking Go to Research Study 3 47% Guidance on evaluating studies 7% MZ twins (19 pairs) DZ twins (14 pairs)

Explanations: genetics Return to sleepwalking menu Research study 2: Lecendreux et al (2003) Go to Research Study 1 What do you think Lecendreux et al found? Click on the button to find out: Results Concordance rate for sleepwalking Go to Research Study 3 Guidance on evaluating studies MZ twins DZ twins

Explanations: genetics Return to sleepwalking menu Research study 2: Lecendreux et al (2003) Go to Research Study 1 What do you think Lecendreux et al found? Click on the button to find out: Results Concordance rate for sleepwalking Go to Research Study 3 50% 10-15% Guidance on evaluating studies MZ twins DZ twins

Explanations: genetics Research study 3: Bassetti (2002) suggests that the same HLA gene abnormality that is implicated in Narcolepsy, may be associated with sleepwalking. He found that 50% of sleepwalkers that he tested had a version of the HLA gene found only in 24% of the non-sleepwalkers Can you think of any problems with drawing conclusions from this piece of research? Return to sleepwalking menu Go to Research Study 1 Go to Research Study 2 Guidance on evaluating studies

Sleepwalking Explanations: stress-diathesis
Return to sleepwalking menu This theory suggests that a genetic predisposition towards sleepwalking will be triggered by external factors Factors that increase the risk of sleepwalking Guidance on using IDA for theories of sleepwalking Click on the boxes to reveal what they are: Hormonal changes associated with menstruation Hormonal changes associated with puberty Stress or other psychiatric conditions Having a fever Sleep deprivation Alcohol

Guidance on evaluating studies When evaluating studies of sleepwalking think about the following points: Return to sleepwalking menu Are there any problems with making generalisations from this study? Are there any problems with attempting to establish a cause and effect relationship from this study? What are the positive points relating to the way the study was carried out? What method is being used? Are there any problems with using this method? What conclusion is the study attempting to draw? Return to main menu Play slide again

The nature nurture debate Return to sleepwalking menu
Guidance on using IDA to evaluate theories of sleepwalking The nature nurture debate Approaches Which approaches are used in this explanation? Does the explanation fall on the nature or nurture side of the argument? Are there any consequences of this (socially sensitive)? Could we explain the sleepwalking using the other side of the argument? If there is more than one, how could that be considered an advantage? Why does it matter? Are there any factors that have not been taken into account? Return to sleepwalking menu Return to main menu

Narcolepsy Click on the section you would like to go to:
Guidance on evaluating studies Explanations of narcolepsy: the role of hypocretin Guidance on using IDA for narcolepsy Explanations of narcolepsy: genetics Return to main menu

More information on hypocretin Return to narcolepsy menu
Explanations: The role of hypocretin (Hcrt) It has been suggested that narcolepsy is caused by the loss of cells in the hypothalamus that secrete Hcrt More information on hypocretin Study 1 Study 2 Return to narcolepsy menu

Narcolepsy Explanations: The role of hypocretin (Hcrt)
Go to study 2 Narcolepsy This study only shows that cells in the lateral hypothalamus (LH) are related to a decline in Hcrt. It is not a study of narcolepsy itself. As humans with narcolepsy have a more than 80% reduction in CSF Hcrt, we can presume they will have a reduced number of cells in the LH Explanations: The role of hypocretin (Hcrt) Guidance on evaluating studies Research study 1: Gerashchenko et al (2003) Return to narcolepsy menu Destroyed the cells in the lateral hypothalamus in rats with a neurotoxin. They found a relationship between the number of cells lost and a decline in the levels of Hcrt in the cerebrospinal fluid (CSF). A 73% decline in Hcrt neurons resulted in a 50% reduction in CSF Hcrt Was that worth destroying my brain for? What does the rat have to say about it all? Click on the rat to see his interpretation of the study

Narcolepsy Explanations: The role of hypocretin (Hcrt)
More information on Parkinson’s disease Explanations: The role of hypocretin (Hcrt) Go to study 1 Research study 2: Guidance on evaluating studies Thannickal et al (2007) People with Parkinson’s disease show sleep complaints that strongly resemble narcolepsy. Parkinson’s is a degenerative brain disorder which involves the loss of cells in many brain areas. Thannickal et al conducted a post mortem analysis of the brains of people who had suffered Parkinson’s disease and found that the brains had lost up to 62% of the cells that contain Hcrt. It is further supported by other research which has shown reduced levels of Hcrt in the CSF of people with Parkinson’s disease Return to narcolepsy menu

Return to narcolepsy menu
Explanations: Genetics Research has indicated that there is a genetic link in narcolepsy in dogs. It was discovered in the 1970s that certain breeds of dog appeared to have an inherited form of narcolepsy. This led to the establishment of a breeding colony of narcoleptic dogs and a concerted effort to find the gene or genes responsible for the disorder study 1 study 2 Return to narcolepsy menu Click on this picture to see a film of a narcoleptic dog

Narcolepsy Explanations: Genetics But... Research study 1:
Click on the statement you think is correct: Nishino & Mignot (1997) Narcoleptic Doberman Pinschers have a genetic mutation affecting Hcrt Research has shown that human narcloleptics also have a faulty Hcrt gene But... Research has shown that human narcoleptics do not have a faulty Hcrt gene Can we generalise to humans? Guidance on evaluating studies Return to narcolepsy menu Go to study 2

Narcolepsy Explanations: Genetics Research study 2: Go to study 1
Guidance on evaluating studies Explanations: Genetics Research study 2: Return to narcolepsy menu Sixteen identical twin pairs with at least one narcoleptic in each pair were studied. In only four of the pairs did both twins have the condition This would suggest that: This is weak support for a genetic link in narcolepsy (Click on the statements you think are correct) The research suggests that genetics are more important than environment in narcolepsy It seems highly unlikely that genetics alone can explain narcolepsy. It is the exception rather than the rule that narcolepsy runs in families This is good evidence that narcolepsy is caused by genetic factors It seems likely that a genetic vulnerability must be combined with environmental factors to trigger the disorder Despite the lack of genetic abnormality in humans, 90% of narcoleptics have extremely low levels of Hcrt

Guidance on evaluating studies When evaluating studies of narcolepsy think about the following points: Return to narcolepsy menu Are there any problems with making generalisations from this study? Are there any problems with attempting to establish a cause and effect relationship from this study? What are the positive points relating to the way the study was carried out? What method is being used? Are there any problems with using this method? What conclusion is the study attempting to draw? Return to main menu Play slide again

Guidance on using IDA to evaluate theories of Narcolepsy Reductionism Approaches Which approach is used in this explanation? Is the explanation reductionist? How is it reductionist? How does the reductionist nature of the research affect its ability to explain narcolepsy? How could the reductionist nature of the explanation be considered socially sensitive? Which approaches have not been considered? Why does it matter? Are there any factors relating to other approaches that have not been taken into account? Return to narcolepsy menu Return to main menu

Explanations of Disorders of Sleep

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