The prevalence of insomnia in Spain: A stepwise addition of ICSD-3 diagnostic criteria and notes

Studies on the prevalence of chronic insomnia disorder often show disparate results. Although a consensus now exists among the three main classification systems for diagnostic criteria, most prevalence studies are only based on clinical criteria defining insomnia syndrome (night and daytime symptoms) with time criteria (weekly frequency and duration). The aim of this descriptive study was to thoroughly assess the inclusion and exclusion criteria, notes and differential diagnosis for chronic insomnia disorder according to the International Classification of Sleep Disorders, 3rd edition (ICSD-3), and ascertain its current prevalence in the Spanish general adult population. The prevalence of insomnia symptoms was 43.4%, chronic insomnia syndrome was 13.7%, and chronic insomnia disorder was 14.0% (women 14.6%, men 13.4%; 18-34 y.o. 11.1%, 35-54 y.o. 11.5%, 55+ y.o. 17.9%). The latter two definitions showed close prevalence results because figures from inclusion and exclusion criteria and notes practically matched and cancelled each other out. A thorough assessment of the prevalence of chronic insomnia disorder would require that, in addition to clinical and time criteria, inclusion and exclusion criteria and modifiers be considered. These elements differ according to sex and age, and strongly influence the results. They included opportunity for sleep, associated sleep disorders, physical problems such as chronic pain, and, notably, asymptomatic patients dependent on prescription drugs for sleep. Current data suggest that the prevalence of chronic insomnia disorder in Spain has more than doubled in 20 years, with an increase of almost 47%.