"She was cooperative and there were no issues with her arrest."
The 23-year-old was charged with a misdemeanor and transferred to the Van Nuys jail for booking, according to People, which added she was subsequently released around 10:30AM.
Pratt had been at a birthday party for former I'm a Celebrity... Get Me Out of Here! participant Holly Montag at L.A. nightclub Empire, according to People.
"Just finished dinner and going to Empire but im pretty tired aka yes i am the party pooper :(" wrote Pratt in a posting to her Twitter account around 11PM.
While Pratt can currently be seen on The Hills' fifth-season episodes -- which air in the Tuesdays at 10PM ET/PT timeslot on MTV -- she recently stated that she's not sure how much more filming of the reality series she can take.