Sleep-EEG patterns of school children suffering from symptoms of depression compared to healthy controls

Depression in children is often an elusive disorder and its diagnostic tools are a matter of controversy. Several scales have been developed in an attempt to specifically detect some of the major aspects of depression, i.e. anhedonia, sadness, hopelessness. On the other hand, in adults depression frequently induces changes in sleep patterns, particularly a shortening in REM sleep latency. The alteration of sleep patterns in depressed children has been a matter of controversy. It is possible that a diagnostic deficiency might be the source of the contradictory reports. In the present study, The Child Depression Inventory, a rating scale specifically developed for child depression was applied to 396 school children (8-12 years of age). Nearly 15% of the children (N=45) obtained scores higher than the established limit in this test for normal healthy subjects. A sample of children found within the highest (N=25) and within the lowest (N=25) scores in the scale were selected. After a clinical evaluation, only those who meet the inclusion criteria (N=21 for depressed and N=7 for healthy controls) were electroencephalographically recorded. Children with depressive symptoms showed a significant shortening in REM sleep latency (mean=108 min) when compared to non-depressed (mean=150 min). In addition, significant increases were observed in sleep latency, REM sleep duration and the number of awakenings. Furthermore, results showed an unexpected high frequency of EEG abnormalities in children with depressive symptoms (75%) characterized by sharp waves and polyspikes in the frontal region. The present results support the notion that depression, in children, is accompanied by changes in sleep patterns, mainly concerning REM sleep.