Nosology and prevalence of sleep disorders

Although the initial sleep disorders classifications provided a framework for categorizing diagnoses, these early instruments had a number of limitations. Among their shortcomings were a lack of specific diagnostic criteria, limited clinical validation, and an overreliance on sleep laboratory findings. As a result, many of the diagnoses were not only poorly substantiated, but they lacked clinical relevance. Also, because of a fusing of diagnoses, a causal relationship was implied that may have been nonexistent and could misdirect the treatment focus. The ICD-10 represents a clinically based diagnostic classification. Furthermore, this classification system includes diagnostic criteria and encourages multiple diagnoses for a more complete description of the patient's clinical presentation. In addition, the ICD-10 allows for differentiation of psychogenic, developmental, and organic factors. Finally, it can be fully applied in the office setting, which allows physicians to maximize their interviewing and assessment skills to complete the diagnoses and subsequent treatment plans. Thus, this classification system strongly reinforces the doctor-patient relationship. It also facilitates consideration of the entire scope of the patient's problems in a truly biopsychosocial perspective. The prevalence of insomnia ranges across studies from 20 to 30% of the adult population. Before adulthood, its prevalence is below 2%. About 5% of adults complain of excessive daytime sleepiness. Among the conditions of excessive daytime sleepiness, narcolepsy has a prevalence of 0.1% and sleep apnea not more than 1% in the general adult population. Nightmares have a prevalence of about 5% in adulthood and 20% in childhood. Sleepwalking and night terrors have a prevalence of less than 1% in adulthood and 15 and 5%, respectively, in childhood.(ABSTRACT TRUNCATED AT 250 WORDS)