One-fifth of patients consulting in primary care have insomnia1 and prevalence in the population ranges from 10–12% to over 20% in older adults.2 It is the most common symptom of mental illness, regardless of age, sex, or ethnic group.3 Insomnia is more common than worry, and twice as common as anxiety or depressive symptoms. Typically, insomnia is associated with reduced daytime alertness and productivity, poorer quality of life, impaired relationships, and increased ill health.4 It is the largest, potentially treatable, risk factor for depression5 and is a major cause of accidents.6
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