Christian rocker Mac Powell has asked fans to pray for his ailing wife after doctors discovered "bleeding on her brain".

The former Third Day frontman reached out to followers on Instagram over the weekend (30Nov19), revealing his spouse, Aimee, had been hospitalised after suffering from a bad headache.

A CT (computed tomography) scan indicated she had "bleeding on her brain", which doctors believed was an aneurysm, and she underwent surgery to treat the injury.

"In her procedure they were able to put in 2 coils which will keep the aneurysm from bleeding and possibly rupturing," Powell explained, beside a photo of his wife in her hospital bed, with her mother by her side.

"Her head is hurting really bad. She'll be kept for many days to be tested and monitored. Thankful for many friends, family, and prayers!"

He went on to express his gratitude for the outpouring of heartfelt messages he had received after going public with the health crisis, and urged fans to "keep praying" as she began the recovery process.

"She hasn't eaten in probably 36 hrs (hours) or so," he updated followers on Sunday. "Pray that her appetite starts to return so that she'll get the strength to start moving a little bit.

"All signs are good so far. There doesn't seem to be any negative neurological signs yet for physical or mental deficiencies. Thanks for your love and prayers!"

Powell fronted Third Day for almost three decades before the band called it quits last year (18).