Sinead O'Connor has revealed that she cancelled her shows for the remainder of the year because her son is battling a "life-threatening medical condition".

Exhaustion was originally cited as the reason why the 49-year-old singer pulled out of this weekend's show at the Galway International Arts Festival and all other gigs planned for the remainder of 2015.

But O'Connor has posted a message to fans on her Facebook page, explaining the real reason behind her decision to pull out of gigging for the rest of the year.

She wrote: "My child has been suffering with a life-threatening medical condition since early March 2015. It is the type of condition my child will definitely survive, if correct care is taken and is supervised by myself. Otherwise there is no guarantee.

"That is the plain truth."

"Needless to say, this has been and remains a severe family crisis. Like any mother, I have been up all day and night every day and night since I found out my child is suffering.

"Studying and learning all I can so that I might help not only the suffering child, but those of my other children who are naturally affected by the situation."

She had intended to tour until recent events dictated otherwise, when O'Connor felt she had to be at home by her child's side.

"Seven nights before I arrived in Las Vegas for the Conor McGregor fight, my child took a turn for the worst, and I became frightened," she recalled.

"I have been instructed by my child's doctor not to work until my child has fully recovered."