Prevalence of insomnia and sleep characteristics in the general population of Spain.

OBJECTIVE: The goals of this study were to estimate the prevalence of insomnia symptomatology and diagnoses in the Spanish general population and to determine if certain sleep parameters were related to specific insomnia symptoms.
METHODS: This is a cross-sectional telephone survey performed in the general population of Spain using a representative sample of 4065 individuals aged 15years or older. The participation rate was 87.5%. Interviews were conducted using the Sleep-EVAL system. The questions were related to sociodemographic characteristics, sleep-wake schedule, events occurring during sleep, insomnia symptoms, daytime consequences and DSM-IV diagnoses of sleep disorders.
RESULTS: Overall, 20.8% (95% C.I. 19.6-22.1%) of the sample reported at least one insomnia symptom occurring at least three nights/week. The prevalence was higher in women than in men (23.9% vs. 17.6%) and increased with age. Difficulty maintaining sleep at least three nights/week was the most prevalent symptom. DSM-IV insomnia disorder diagnoses were found in 6.4% (95% C.I. 5.6-7.1%) of the sample. Delayed bedtime and wake-up time, irregular bedtime hours and hypnagogic hallucinations were the most frequent in participants who had difficulty initiating sleep. Perception of light and "too short" sleep were the most frequent in participants who had early morning awakenings. Participants who had a non-restorative sleep were more likely to extend sleep on days off than other insomnia participants. Medical consultations in the previous year were more frequent in insomnia participants compared to participants without insomnia. One-fifth of insomnia participants were using sleep-promoting medication.
CONCLUSIONS: Insomnia is frequent in Spain, affecting up to one in five individuals. Results show that insomnia is multidimensional and needs to be assessed as such.