The Disney star has battled substance abuse for years and spent some time in rebab in 2010.
Demi Lovato's assistant thought she was dead when she found her unconscious last week.
The 25-year-old singer's staff flew into a state of panic when they found her lying on the floor at her home in Los Angeles, California, last week following a suspected overdose.
A source told TMZ.com "Thebodyguard somehow knew there was an emergency at Demi's home a week ago and when he entered the home Demi's assistant was screaming: 'She's dead, she's dead!'
"The bodyguard rushed to Demi's side and it appeared she was not breathing. There was blood on her pillow ... an ominous sign, because it's evidence of haemorrhaging. It appears there was also vomit and her airways may have been clogged. The bodyguard administered some sort of first aid to keep Demi alive before paramedics arrived."
It's believed the paramedics arrived and administered Narcan, which reverses the effects of an opioid overdose, before rushing the 'Sorry Not Sorry' hitmaker to Cedars-Sinai hospital.
The former Disney star has spent the past week being cared for by doctors after suffering complications - including a high fever and severe nausea - from the alleged overdose.
However, it's thought she'll be ready to leave hospital this week and she's reportedly agreed to head back into rehab to help her beat her addictions and get back on the road to sobriety.
A source said recently that Demi's family have "squarely raised the issue of rehab with her" after putting off the talks when she became seriously ill due to the complications.
But Demi - who revealed in new track 'Sober' in June that she had relapsed after five years of sobriety - is "serious about her sobriety", and will "do whatever it takes" to get sober.
An insider explained: "Demi has told the people close to her that she is serious about her sobriety, and plans to do whatever it takes to maintain a healthy lifestyle moving forward."
