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Chronic insomnia is highly complex and it is unlikely that there is only one underlying cause; the
large number of factors makes it very difficult to conduct research because studies only find small
effects it is difficult to draw firm conclusions from research; may effect external reliability
Causes of insomnia
Secondary when there is a single, underlying medical, psychiatric or environmental cause in these cases,
insomnia is a secondary symptom of another disorder, such as depression or heart disease. Secondary
insomnia is typical of people who do shift work or have a circadian rhythm disorder such as phase delay
syndrome. Insomnia can also be the result of environmental factors, such as too much caffeine or alcohol.
Ohayon and Roth 2003: studied almost 15000 Europeans with insomnia and found that insomnia
often preceded cases of mood disorder, as opposed to following it. This means that in some cases
it might be helpful to treat insomnia regardless of whether it is primary or secondary
Primary describes cases where insomnia occurs on its own, with no known cause, for more than one
month (DSM definition). Psychological states, though they may be felt (i.e. an individual may feel stressed
or depressed) are not the main problem. Sometimes insomnia may have an identifiable cause which has
now disappeared, but the disorder continues due to the expectation of sleep difficulty.
Epsie 2002: perpetuating factors such as being tense when going to bed due to previous sleep
problems are key to chronic insomnia
Age and gender - older women are more likely to suffer from insomnia. In older people, other conditions
such as arthritis and diabetes may disrupt sleep and lead to insomnia. Increased risk in women could be
related to age-related hormonal fluctuations i.e. menopause
Parasomnias sleep apnoea (a condition in which sufferers stop breathing for periods of a few seconds to
minutes at regular intervals during sleep) and other parasomnias such as snoring, sleep walking and teeth
grinding all disturb sleep and thus increase likeliness of that individual experiencing insomnia
Personality insomniacs are more likely to internalise psychological disturbance rather than act
Kales et al 1976: researchers in this study proposed that internalisation leads to higher levels of
emotional arousal and increased likeliness of feeling anxious, which is a risk factor in insomnia
Genetics twins studies provide evidence that there may be a genetic vulnerability linked to insomnia.
There are some predisposing, precipitating and perpetuating components.
Watson et al 2006: 50% of the variance in the risk for insomnia could be attributed to genetic
Bonnet and Arand 1995: insomniacs are more likely to experience hyperarousal, which would
make it more difficult to get to sleep could explain why only some people develop insomnia in
response to stress, shift work, jet lag etc.
Diathesis-stress model proposes that vulnerability alone is not enough for a disorder to develop