Pratt, 23, was arrested at 3:45 a.m. in Hollywood, a spokesman for the Los Angeles police told E! News. Police brought her to Van Nuys jail where her bail was set at $5,000.
She was ticketed and released later Sunday morning and was not required to post bail, a spokesperson at the Van Nuys Division told MTV News.
Members of "The Hills" crew were out celebrating co-star Holly Montag's 26th birthday at Empire, a Los Angeles nightclub. The night must not have gone how Pratt expected, as hours before her arrest she tweeted that she was already 'pretty tired.'
This isn't Pratt's first arrest. In May 2006 she was arrested along with "Lost" director Jack Bender's daughter for shoplifting $2000 worth of clothing at Neiman Marcus in Honolulu, police told an ABC affiliate in Hawaii.