Facts and Figures
DSPS commonly causes severe insomnia, particularly among adolescents and young adults, with the highest prevalence among those who are about 20 years of age. Prevalence is 7–16% in countries that report DSPS prevalence, including Brazil, Japan, Norway, and the United States. Forty percent of patients have a family history of DSPS. DSPS is diagnosed in approximately 10% of patients who seek medical attention for chronic insomnia.