What causes delayed sleep-wake phase disorder (DSWPD)?

What causes delayed sleep-wake phase disorder (DSWPD)?

The exact cause of this disorder is not completely known. However, approximately 7% to 16% of adolescents have DSWPD. Thus, it is a common disorder. Scientists think DSWPD may be an exaggerated reaction to the normal shift in the internal clock that is seen in many adolescents after puberty. It is important to understand that this is not a deliberate behavior. DSWPD most commonly occurs during adolescence, but cases have been reported during childhood; it is rare for it to begin after early adulthood.