NEW YORK - Sleep problems and
depression in children may share a genetic source, a study of twins hints.
"A range of sleep difficulties are associated with depression in school-aged
children, and the overall association between the two difficulties maybe largely
influenced by genes," report Dr. Alice M. Gregory of Kings College London, UK,
and colleagues in the journal Pediatrics.
Sleep problems are thought to be related to anxiety and depression, but this
relationship is complex and poorly understood. To help clarify the role of
genetic and environmental factors in the anxiety-depression-sleep problem
association, Gregory and her team studied 300 pairs of eight-year-old twins.
Twin studies are useful in teasing out genetic and environmental influences,
the researchers note, because identical twins share the same genes and the same
environment, while fraternal twins' genetic relatedness is the same as any other
sibling pair, although their environment could be considered identical.
Parents reported any sleep problems the children had and the children were
assessed for anxiety and depression.
While anxiety showed little relationship to sleep problems, children with
sleep problems had higher levels of depression, the researchers found. The sleep
problems included resistance at bedtime, delays in getting to sleep, anxiety
associated with sleep, as well as sleep terrors and sleepwalking, related
conditions called parasomnias.
Relationships between sleep and depression were stronger among identical twin
pairs. According to the investigators, genes played the greatest role in this
relationship, while the influence of environment was smaller.
"The large overlap between genes influencing depression and those influencing
sleep problems suggest that it may be worth exploring whether genes that are
known to influence depression are associated with sleep problems, and vice
versa," Gregory and her team conclude. Genes related to the neurotransmitters
serotonin or dopamine may be candidates, they add.
The findings also suggest that doctors should check for sleep problems in
their young patients who show signs of depression, and vice versa, they add.
SOURCE: Pediatrics, September 2006.
