Superstar singer Whitney Houston, who was found dead at the Beverly Hilton Hotel Saturday afternoon, habitually took Xanax before performances to calm her nerves, TMZ reported Sunday.

According to TMZ's sources, Whitney Houston claimed to have anxiety and panic attacks. The Xanax pills reportedly helped to alleviate them. The people in her hotel suite Saturday, including her hairdresser, stylist and bodyguard, were aware that she would take pills before shows but reportedly did not see her take any that day.

Whitney was supposedly happy and in a good mood and was said to be excited to be performing at Clive Davis' annual pre-Grammy party Saturday night.  

TMZ reported Sunday morning that the singer was found face-down in the hotel bathtub. According to sources, her stylist, hairdresser and bodyguard were in the room at the time and became concerned after realized Houston had been in the bathroom for more than an hour.

They knocked on the door and, after getting no answer, the hairdresser went in to check on the singer. The woman screamed and one of the bodyguards ran in and pulled Whitney Houston from the tub.

Whitney Houston was found with her face down in the water. Her legs were up, as if she had slid down the back of the tub, according to TMZ.

Sources told TMZ that Houston's body was very cold when it was discovered.

Apparently on Friday night, the singer had been partying a lot - drinking and mixing alcohol with Xanax. TMZ notes that this combination could cause someone to fall asleep in a bathtub.

The Daily Mail reported the suite was littered with bottles of prescription pills. 

On the Thursday evening before her death, the singer was spotted out in Hollywood where she got into fights partied heavily, drank and chatted loudly with friends at the hotel bar, according to TMZ.

The Los Angeles County Coroner could perform an autopsy as early as Sunday to determine the exact cause of death. No illicit drugs have been found.

Whitney Houston would have attended Clive Davis' annual pre-Grammy bash on Saturday at the Beverly Hilton Hotel.

It's a great time where everybody can set down their swords, so to speak, Davis told the Los Angeles Times. I was grateful that, inviting them to my home, that they would feel comfortable and just keep coming back, and they've kept coming back every year to where it's expanded to be this incredible haven for musicians.

Davis played a huge part in fostering Houston's success while working as a lawyer at Columbia Records. Houston was expected to party with the likes of Quincy Jones, Tony Bennett, Akon, Cee Lo Green, Miley Cyrus, Sean Puffy Combs, Jennifer Hudson, Jackson Browne, Elvis Costello and Diana Krall at the Grammy fete.

Whitney Houston was just 48 years old. She leaves behind her 19-year-old daughter, Bobbi Kristina.