This study provides data on the prevalence of diagnosable sleep disorders in preschoolers and examined the relationship between specific sleep disorders and a range of DSM-4–defined psychiatric symptoms.
All children born in 2003 or 2004 in Trondheim, Norway, who attended regular community health checkups for 4 year olds were asked to participate (97.2% attendance; 82.0% consent rate, N = 2475). A screen-stratified subsample of 1250 children was recruited to participate in an additional comprehensive study that included a structured diagnostic interview (the Preschool-Age Psychiatric Assessment). Nine hundred ninety-five parents (79.6%) completed the interview.
The estimated sleep disorder rate was 19.2%. Rates of specific disorders were as follows: primary insomnia (16.6%), primary hypersomnia (0.8%), nightmare disorder (2.2%), and sleepwalking disorder (0.7%). When adjusted for a range of common psychiatric symptoms, primary insomnia was specifically related to symptoms of depression, generalized anxiety disorder, separation anxiety, and specific phobia. When sleep problems were excluded as a symptom of depression, the association between depression and primary insomnia was no longer significant. Nightmare disorder was significantly related to generalized anxiety disorder.
This first study of the prevalence and comorbidity of diagnosable sleep disorders in preschoolers indicates that primary insomnia is common in young children, whereas other sleep disorders are rare. Sleep disorders are related to psychiatric symptoms, particularly symptoms of anxiety disorders.