Hierarchy of insomnia criteria based on daytime consequences

To explore how insomnia symptoms are hierarchically organized in individuals reporting daytime consequences of their sleep disturbances.

This is a cross-sectional study conducted in the general population of the states of California, New York, and Texas. The sample included 8937 individuals aged 18 years or older representative of the general population. Telephone interviews on sleep habits and disorders were managed with the Sleep-EVAL expert system and using DSM-IV and ICSD classifications. Insomnia symptoms and global sleep dissatisfaction (GSD) had to occur at least three times per week for at least three months.

A total of 26.2% of the sample had a GSD. Individuals with GSD reported at least one insomnia symptom in 73.1% of the cases. The presence of GSD in addition to insomnia symptoms considerably increased the proportion of individuals with daytime consequences related to insomnia. In the classification trees performed, GSD arrived as the first predictor for daytime consequences related to insomnia. The second predictor was nonrestorative sleep followed by difficulty resuming sleep and difficulty initiating sleep.

Classification trees are a useful way to hierarchically organize symptoms and to help diagnostic classifications. In this study, GSD was found to be the foremost symptom in identifying individuals with daytime consequences related to insomnia.