Sufjan Stevens revealed he has been hospitalised for two weeks after being diagnosed with the autoimmune disease Guillain-Barré syndrome (GBS).

In a lengthy Instagram post shared on Wednesday, the Grammy-nominated singer shared a selfie from hospital and updated fans on his condition.

"Last month I woke up one morning and couldn't walk," the Fourth Of July singer, 48, wrote. "My hands, arms and legs were numb and tingling and I had no strength, no feeling, no mobility. My brother drove me to the ER and after a series of tests - MRIs, EMGs, cat scans, X-rays, spinal taps (!), echo-cardiograms, etc. - the neurologists diagnosed me with an autoimmune disorder called Guillian-Barre Syndrome."

"Luckily there's treatment for this," Sufjan continued, "they administer immuno-hemoglobin infusions for five days and pray that the disease doesn't spread to the lungs, heart and brain. Very scary, but it worked."

The singer said he owed the doctors his "life" and went on to reveal that he was currently undergoing "intensive physical therapy/occupational therapy, strength building etc to get my body back in shape and to learn to walk again".

He added, "It's a slow process, but they say I will 'recover,' it just takes a lot of time, patience and hard work."

Sufjan explained the illness was the reason for not doing interviews to promote his new album, Javelin, due for release on 6 October.