It is perfectly normal for people to feel dissatisfied by their sleep from time-to-time and the word ‘insomnia’ is thrown around a lot but – how is insomnia defined?
The diagnostic criteria for insomnia are listed in the Diagnostic and Statistical Manual (DSM), the manual used by clinicians and researchers to diagnose and classify mental disorders. In the fifth edition, published in May 2013 (DSM-5), insomnia disorder is defined as a combination of both dissatisfaction with sleep and a significant negative impact on daytime functioning.
Dissatisfaction with sleep is further defined as difficulty initiating and/or maintaining sleep or non-restorative sleep, on at least three nights per week for at least 3 months, despite adequate opportunity to sleep. Negative daytime impacts can include significant fatigue, sleepiness, poor concentration, low mood, or impaired ability to perform social, occupational or caregiving responsibilities.
Insomnia as a target for intervention, not just a symptom
The traditional view, which was reflected in earlier editions of the DSM, was to define insomnia as either primary (i.e. no other conditions deemed to be responsible for the poor sleep) or secondary (i.e. another disorder causally responsible for the poor sleep). In practice determining cause and effect is very difficult, if not impossible. Bidirectional or interactive effects between insomnia and certain co-existing conditions, such as depression, are now widely accepted. Importantly, DSM-5 removed the primary and secondary causal attribution labels. ‘Insomnia disorder’ is now recognized as a condition requiring independent clinical attention, regardless of other medical problems that may be present.
Causes of insomnia – “why can’t I sleep?”
It would be great to think that insomnia had a single cause! It usually does not – The ‘3 Ps’ model, designed to help people understand the development and persistence of health problems, was brought into research on poor sleep by Dr Art Spielman in the 1980s. The three Ps stand for ‘predisposing’, ‘precipitating’ and ‘perpetuating’ factors:
A predisposition does not ‘cause’ a problem but may increase the likelihood of it occurring. When thinking about insomnia these could include having a family history of poor sleep, generally being a ‘worrier’ or never having been a ‘good sleeper’, for example.
Another word for these could be ‘triggers’ and may include such things as lifestyle changes, a house move or promotion at work, the development of an illness or birth of a baby for example. Indeed a study published in 2004 found that 60% of patients with insomnia could identify a trigger for their sleep disturbance, and these tended to be around family, work/school and health (Bastien et al. 2004).
These would cover any factors which might be seen to maintain or even exacerbate the problem e.g. heightened anxiety/arousal levels for or the development of depression which may represent barriers to recovery. It may also be the case that behaviors or coping strategies (e.g. napping during the day spending excessive amounts of time in bed), developed and implemented over time are involved in the maintenance of insomnia. Thus, insomnia could become learned over months and years, even though the initial stressor that may have been involved in its development has disappeared.
Treatments for insomnia
Following the 3 Ps model, it is clear that perpetuating factors, due to their presumed role in maintaining insomnia, are good candidates for intervention. Indeed this is exactly what Cognitive Behavioral Therapy (CBT-I) attempts to do; targeting maladaptive sleep behaviors and cognitions that are characteristic of insomnia. Other treatments like sleeping pills, may similarly target core features of insomnia, like the racing mind, but at a different level (usually in terms of alterations to neurochemicals involved in the regulation of sleep and arousal, like GABA).