Sleep disorders linked with more severe depression

Nearly three quarters of children diagnosed with major depression also experience insomnia, excessive sleeping (hypersomnia) or both, according to a report in the current issue of the journal Sleep. The study authors found that these children also had more severe symptoms of depression and anxiety.

"What this study shows is that, in depressed youths, not all sleep problems are the same," lead author Dr. Xianchen Liu states in a press release from the American Academy of Sleep Medicine. "Insomnia is the most common problem, but having a combination of insomnia and hypersomia is 'double trouble'."

Differentiating between types of sleep disorders may be important in the treatment of depression, Lui group concludes.

Liu, from the Western Psychiatric Institute and Clinic at the University of Pittsburgh in Pennsylvania, and colleagues compared the clinical profiles of 533 children treated for major depression at mental health facilities in Hungary between 2000 and 2004. The average age was 11.7 years and the average illness duration was 13.8 months.

Full diagnostic interviews of the subjects included questions regarding difficulty falling asleep at night, amount of time spent sleeping, sleep quality, difficulty waking up and falling back to sleep, duration of the problem and napping during the day. Conditions were considered significant if they persisted at least 2 weeks, Liu told Reuters Health.

Responses to interview questions showed that 53.5 percent had insomnia alone, 9.0 percent had hypersomnia alone, and 10.1 percent had both. Among those with hypersomnia, more than half also had insomnia.

"We also wanted to know what unique symptoms related to each condition," Liu added. In fact, they did observe different symptom profiles associated with sleep disturbance.

Those with no sleep disturbances had the least severe depression. In general, those with disturbed sleep exhibited greater depressed mood, irritability, sadness, psychomotor agitation, fatigue, anhedonia, inappropriate guilt, weight loss, daily variation and anxiety disorders, but less oppositional defiant disorder than those with normal sleep patterns.

Insomnia alone was associated with more frequent depressed mood, daily variations, psychological and physical agitation, and feelings of worthlessness, than those with hypersomnia.

Children with hypersomnia were more likely to exhibit weight gain or loss, and were also more likely to have been prescribed a selective serotonin reuptake inhibitor (such as Prozac, and tranquilizers).

"We may be better able to classify children's depression by understanding their sleep disturbances," Wu said. "This may also result in different medications and non-pharmacotherapies depending on the presence of insomnia or hypersomnia."

However, further work needs to be done, he added, to tease out the interplay between disturbances in circadian regulation, abnormal exposure to bright light, altered social interactions, and differences in neurobiological mechanisms or genetic causes.