The 'Nothing Compares 2 U' singer - who underwent a hysterectomy in August - posted a worrying message on Facebook on Sunday claiming she had checked into a hotel in Ireland under a different name and had overdosed.
The 48-year-old star told how she had been "howling, crying for weeks" and insisted she "doesn't matter a shred to anyone" and that her family wouldn't notice for weeks if she ended her life.
Police rushed to her aid and she is being given medical assistance, the MailOnline reports.
The concerning message began: "There is only so much any woman can be expected to bear. What was done to me this week was appalling cruelty."
Another section reads: "This week has broken me. The withholding of my babies from me without any sound reason by their fathers, Frank and Donal, and by Jake and the rest of my family, is a horrific set of betrayals. And has been going on since I had my surgery. The last two nights finished me off. I have taken an overdose. There is no other way to get respect. I am not at home, I'm at a hotel, somewhere in ireland, under another name
If I wasn't posting this, my kids and family wouldn't even find out. Was dead for another fortnight since none of them bother their hole with me for a minute. I could have been dead here for weeks already and they'd never have known. Because apparently I'm scum and deserve to be abandoned and treated like s**t just when I've had my womb and ovaries chopped out and my child is frighteningly sick. I'm such a rotten horrible mother and Person, that I've been alone. Howling crying for weeks. And been told by them all t go f**k myself. I'm invisible. I don't matter a shred to anyone. No one has come near me. I've died a million times already with the pain of it. So yeah.. Strangers like me.. But my family don't value me at all. They wouldn't know if I was dead until weeks from now if I wasn't f***ing informing them now.
well done guys, you've finally got rid of me. Sorry the penny didn't drop sooner. I'm an idiot. When you planned to get me away from my babies did you plan for me losing my mind over it? It being the final straw? For how you're gonna explain why I died? Make sure you tell the truth. (sic)"
In July, Sinead cancelled all her gigs after revealing her son had been battling a "life-threatening illness" since March.
Earlier in the day, Sinead - who has four kids, sons Jake, Shane and Yeshua and daughter Roisin - posted a cryptic message on the social networking site about "people tormenting a cripple" and then waking up the next day as "murderers".
She wrote: "Remember the one about the people who didn't think about what might happen if they didn't stop tormenting a cripple? They found out real hard 'how far is too far' . They woke up next day as murderers, believing they'd gone to bed so high and mighty, and so superior to those they'd deemed 'unfit'. (sic)"
Sinead also posted a message in which she urged "anyone in any doubt as to my fitness as a mother" to contact family services and revealed she had quit music.
She wrote: "I need a new home. And a new job. A new life ... Music is over for me. Music did this. It rendered me invisible. Murdered my soul. I'm never going back to music. (sic)"