Use of marijuana is linked to excessive daytime sleepiness among adolescents, new research shows.
 
 The researchers found that 10 percent of adolescents sent for evaluation of excessive daytime sleepiness with testing results consistent with narcolepsy had urine drug screens positive for marijuana.
 
 Typically, a diagnosis of narcolepsy is made after a clinical evaluation for excessive daytime sleepiness.
 
 "A key finding of this study is that marijuana use may be associated with excessive daytime sleepiness in some teenagers," said senior author Mark Splaingard from Nationwide Children's Hospital in the US.
 
 "Our findings highlight and support the important step of obtaining a urine drug screen, in any patients older than 13 years of age, before accepting test findings consistent with narcolepsy, prior to physicians confirming this diagnosis," Splaingard added.
 
 The 10-year retrospective study involved 383 children.
 
 The study was published in the Journal of Clinical Sleep Medicine.