Narcolepsy – extreme bouts of sleepiness that can strike at any time – affects around 1 in 2,000 people in the US. A new study raises concerns about its diagnosis in adolescents, after it identified marijuana in the urine of some teenagers who had symptoms consistent with narcolepsy.

The researchers say their findings indicate that marijuana use may be linked to EDS in some adolescents, and that urine drug screening should form a part of clinical evaluation for narcolepsy.

Journal of Clinical Sleep Medicine.