August 14, 2009

Science Daily/UT Southwestern Medical Center

Sleep patterns can help predict which adolescents might be at greatest risk for developing depression, a researcher at UT Southwestern Medical Center has found in a five-year study.

Sleep is a biological factor known to be associated with adult depression. Depressed adults experience rapid-eye-movement (REM) sleep earlier in the sleep cycle than people who are not depressed. Until this study, available online and in the July edition of Neuropsychopharmacology, it had been unclear whether this relationship held true in adolescents.

At the start of the study involving 96 adolescents with no evidence of depression or other psychiatric disorders, researchers monitored the sleep cycles of participants for three days and collected saliva and urine samples to record cortisol levels. The teens were then monitored for up to five years.

In addition to the sleep finding, researchers found that at the end of the five-year study period, adolescents with higher cortisol levels were more likely than others to develop depression.

"Depression is not mediated by sleep alone," Dr. Rao said. "If we can identify factors such as sleep and cortisol and their role, we could start the prevention process before the disease leads children and teenagers down a path well behind their peers educationally and socially."

http://www.sciencedaily.com/releases/2009/08/090813083335.htm