Demi Lovato turns 19 – happy birthday!

Since today she had to be present at Kim Kardashian’s wedding, Demi took her chance to party in advance on Thursday.

Lovato shares her birthday with Sober Is Sexy clothing designer Hanna Beth for and the two celebrated together at Beacher’s Madhouse in Hollywood .

Demi sported an extra short silver spiked Marco Marco shoulder dress. The themes of the party were Sober Is Sexy and glam rock.

“There was no alcohol, but an open Red Bull bar,” a partygoer says. “People who weren’t dressed glam rock weren’t admitted.”

“Demi mingled with everyone and was such a sweetheart,” the source adds. “She danced on stage with Hanna Beth, drank Red Bull and danced a lot.”

Having overcome her past struggles, Demi has come back to the front stage. A few weeks ago, she released her new single Skyscraper which she based on her painful experience.

Her third album Unbroken will be available on September 20.