Psychology Sleep Disorders

Types of Insomnia

Onset insomnia: trouble getting to sleep

Maintenance insomnia: trouble remaining asleep

Termination insomnia: waking up too early

Defining Primary and Secondary

Primary: insomnia that occurs on its own for more than one month. 

Secondary: insomnia due to an underlying problem (medical/environmental) 

Hyper Arousal

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Insomniacs can feel less sleepy during the day than non-insomniacs. It's suggested that insomniacs are in a heightened state of physiological arousal. They feel more awake during the day than normal and have difficulty reducing their arousal at night. 

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Evidence to support hyper arousal was done by Vgontzas, who found that insomniacs have higher levels of ACTH and cortisol (both linked to stress/arousal). However, it could just be a side effect of insomnia and could lead to an aeitology fallacy where just because increased levels of ACTH and cortisol are found in insomniacs doesn't mean that they are the cause of insomnia. Therefore more research needs to be done into explaining insomnia as we cannot fully rely on hyperarousal. 

Brain Biochemistry 

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It has been suggested by some psychologists that insomnia is caused by specific changes in the brain chemistry.

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Evidence to support brain biochemistry as the cause of insomnia was done by Winkleman. He found that people who had suffered from insomnia for more than six months have a reduced level of the neurotransmitter GABA. This suggests that this may be the cause for the disorder. However, it is also possible that reduced levels of GABA are an effect of insomnia and because we didn't know their GABA levels before we cannot believe this to be the cause of insomnia so other things such as genetics have to be considered when explaining primary insomnia. 

Genetics

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With more research being done there is growing evidence to suggest that it is possible to have a gentic predisposition towards primary insomnia.

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Evidence to support genetics when trying to find the cause of primary insomnia was done by Beaulieu-Bonneau who reported that 35% of insomniacs surveyed had a first degree relative that also suffered from the disorder. This suggests that it's passed on through genes, but, only 35% had it so therefore it is only a correlation between the two and it could be something like their environment e.g. diet, as they are living in the same conditions. Or it could have been learnt from the relative e.g. a parent, and the child could be imitiating their behaviour through the social learning theory. 

Genetics

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Studies that have been done for insomnia have shown that there is a higher concordance rate in Mz (identical) twins than in Dz (non-identical) twins.

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Evidence to support the influence of genetics and insomnia was done by Joho who studied mice who displayed similar behaviour to human insomnia. he found that there were mutations in the genes that control electrical excitability in the thalamic reticular nucleus (neurons in this area were overactive). This therefore suggests that this part of the brain may be responsible for insomnia. However, it was done only on animals therefore we cannot extrapolate to humans as humans have different brains to that of mice. So we need to look at other explanations when trying to find the cause of primary insomnia. 

Psychological Factors 

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By some psychologists it has been suggested that primary insomnia maybe learnt through classical conditioning (stimulus response associations). 

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Primary insomnia maybe learnt because the insomnia may have occurred from an identifiable cause e.g. a room being too light, even when the original cause has disappeared the person may still expect to have difficulty sleeping (associates bed with not being able to sleep). However, this is supported by therapy used for insomnia (usually behavioural) where you unlearn bad habits therefore classical conditioning could answer why some people have insomnia as they use their behaviour and habits to treat the disorder. 

Drugs

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Insomnia is reported to be a side effect from taking drugs which are used to treat a number of disorders such as hypertension (high blood pressure) - this is probably due to the chemical changes in the body.

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Evidence to support the fact that drugs can increase insomnia have been found in sleeping pills which are taken to help treat insomnia, they can also have negative side effects such as addition, dependency and tolerance. Although these drugs do increase sleep time, evidence shows that sleeping pills give poor quality sleep as they disrupt the natural ultradian rhythm of REM and NREM. Drugs can also lead to increased insomnia when the person stops taking the drugs as the then learn to associate taking the drugs with being able to sleep (classical conditioning). This therefore shows that drugs can influence the cause of secondary insomnia. 

Mental Illness

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Weiss found 72% of psychiatric patients in their study reported sleep problems. Insomnia can be closely linked with depression as it is included in the criteria for diagnosis. this link could be because there are many neurochemicals involved in depression which are important in sleep e.g. serotonin, depression is linked to low levels of serotonin. As when there are high levels of serotonin this leads to sleep so low levels of serotonin could be the reason for having sleep difficulties. Also high levels of cortisol are linked to depression and this may be the reason for hyper arousal and therefore sleep problems. 

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To evaluate mental illness when trying to explain insomnia not all sufferers of depression have sleep problems and vice versa therefore we cannot establish cause and effect as it does not happen to everyone and need to consider of explanations instead of mental illness as the cause for insomnia. 

Brain Injury

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It is said that having a brain injury is a common cause for having secondary insomnia. 

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Evidence to support brain injury as a reason for insomnia was done by Ayalon who estimates that between 40 and 65% of patients who suffer mild brain trauma complain of having insomnia. This could be because of the part of their brain which control the circadian rhythms being altered during the injury, however, not all the people who suffer from insomnia have suffer from any kind of brain injury therefore we cannot say that is the cause for insomnia. Also it is just a correlation and if this was the cause it would be 100% therefore we cannot use this as the cause but we can make correlations between the two.