Precipitants of insomnia have also been studied. Female gender, advanced age, depressed mood, snoring, low levels of physical activity, comorbid medical conditions, nocturnal micturation, regular hypnotic use, onset of menses, previous insomnia complaints, and high level of perceived stress have all been implicated as risk factors the first three factors in particular (female gender, advanced age, and depressed mood) are consistent risk factors ( 7, 17 – 22). Several risk factors for insomnia have been identified. Given all the information available, the prevalence of insomnia symptoms may be estimated at 30% and specific insomnia disorders at 5% to 10% ( 16). According to a 2005 statement by the National Institutes of Health, insomnia has a prevalence of 10% if the definition necessitates daytime distress or impairment ( 15). Similar disparities were shown in a prevalence study from France ( 14). Using the more stringent criteria from DSM-IV, however, 5% of the sample qualified for the diagnosis ( 13). If the symptom of difficulty maintaining sleep was the defining factor, 11.5% of the sample was affected. When insomnia was defined by frequency (symptoms occurring at least 3 nights per week), 17% of randomly selected subjects from the population qualified for the diagnosis. This problem is demonstrated by the findings of a prevalence study from South Korea. Insomnia Definition Enlarge tableĪs a result of these differences in insomnia case definitions, estimates of insomnia prevalence have varied widely, from 10% to 40% ( 5 – 12). Duration of insomnia (at least 1 month of symptoms) is noted in ICSD-2 and DSM IV-TR however, frequency of symptoms is broached only in ICD-10. ICD-10 uses the broadest approach, categorizing insomnia based on underlying pathology: nonorganic insomnia and nonorganic disorder of the sleep-wake schedule (see Table 2) ( 4). The DSM IV-TR separates out primary insomnia (insomnia symptoms associated with distress or daytime impairment) from other “dyssomnias,” such as a breathing-related sleep disorder ( 3).

These categories also contain insomnia caused by a mental disorder, substance, or medical condition.

Examples include adjustment insomnia (insomnia temporally related to an identifiable stressor) and psychophysiologic insomnia (increased arousal and conditioned sleep difficulty) ( Table 2) ( 2). ICSD-2 subdivides insomnia into descriptive, etiologic categories. The three main diagnostic manuals, International Classification of Sleep Disorders (ICSD-2) ( 2), Diagnostic and Statistic Manual (DSM IV-TR) ( 3), and International Classification of Disease (ICD-10) ( 4), vary in their approach to defining insomnia ( Table 1). Do insomnia and depression coexist in an individual as separate disorders? Is insomnia only one symptom in the larger context of depression? Did insomnia secondarily developed as a distinct disorder from a primary depressive disorder? An illustration of this idea is the overlap between insomnia and depression. This picture is further complicated by considerations of insomnia as either a comorbid condition as a symptom of a larger sleep, medical, or psychiatric disorder or as a secondary disorder ( 1). Insomnia has also been defined by subtypes based on frequency duration (acute versus chronic) and etiology. Broadly speaking, insomnia has been viewed as a symptom and as a disorder in its own right. The prevalence of insomnia varies depending on the specific case definition.

Insomnia icd 10 b