Britney Spears' using drug to treat excessive daytime sleepiness

Photographers snapped a package of Provigil, a prescription drug used to treat excessive daytime sleepiness (and narcolepsy), in Britney Spears' open purse as she made her way to her first co-parenting class with Kevin Federline Wednesday at the Beverly Hills Hotel, US reports.

“Unlike a traditional stimulant with side effects such as hyperactivity and inattentiveness, the primary effect of this medication is only to help keep you from falling asleep,� Dr. Mark Milstein, a New York neurologist, tells Usmagazine.com. “Somebody who is living a celebrity lifestyle, who frequently has to be up very early one day and then very late the next, could develop very disordered sleep patterns�

Provigil cannot be abused as a drug, the doctor says.