Insomnia

Characterisation

Affecting between 30 – 45 percent of adults,¹ insomnia is characterised as:²

Difficulty falling asleep
Difficulty maintaining sleep
Poor quality of sleep or non-refreshing sleep

All of these characteristics are associated with daytime distress or poor daytime functioning, such as fatigue, and lack of concentration. It is estimated that primary insomnia, defined as insomnia with no other underlying condition as its cause affects 1-10 percent of the general population, increasing to up to 25% in the elderly.¹

Primary insomnia

The DSM-IVTR diagnostic criteria for primary insomnia are:

the predominant complaint is difficulty initiating or maintaining sleep, or non-restorative sleep, for at least 1 month
the sleep disturbance (or associated daytime fatigue) causes clinically significant distress, or impairment in social, occupational, or other important areas of functioning
the sleep disturbance does not occur exclusively during the course of narcolepsy, breathing-related sleep disorder, circadian rhythm sleep disorder, or a parasomnia
the disturbance does not occur exclusively during the course of another mental disorder, e.g., major depressive disorder, generalised anxiety disorder, a delirium
the disturbance is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition.³

Key elements for the definition of primary insomnia include difficulties to initiate or maintain sleep and/or non-restorative sleep (inadequate sleep quality) as well as negative effects on subsequent daytime functioning as a result of a poor quality of sleep.⁴

References:
1. Wade AG, Zisapel N, Lemoine P. Prolonged-release melatonin for the treatment of insomnia: targeting quality of sleep and morning alertness. Ageing Health 2008; 4(1): 11-12
2. Diagnosis and statistical manual of mental disorder for primary insomnia, fourth edition, American Psychiatric Association, 2000:597-661
3. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Fourth edition text revision (DSM-IV-TR). Washington DC: American Psychiatric Association, 2000.
4. Wade AG, Ford I, Crawford G, et al. Efficacy of prolonged release melatonin in insomnia patients aged 55–80 years: quality of sleep and next-day alertness outcomes. Curr Med Res Opin 2007; 23 (10): 2597– 2605.