Joni Mitchell in Intensive Care

Joni Mitchell was rushed to the hospital after being found unconscious at her Los Angeles home yesterday afternoon, TMZ reports. The singer-songwriter regained consciousness in the ambulance and "is currently in intensive care undergoing tests," according to official website jonimitchell.com, which urged fans to "Light a candle and sing a song, let's all send good wishes her way." In December, the 71-year-old Canadian revealed that she has Morgellons disease, which she says has kept her from performing, the BBC reports.

What is Morgellons disease? The BBC terms it a "rare skin condition"; the New York Times subs the word "mysterious" for rare. The Mayo Clinic's definition is much more thorough, confusing, and wild: It characterizes the disease as "an uncommon, unexplained skin disorder characterized by sores, crawling sensations on and under the skin, and fiber-like filaments emerging from the sores. It's not certain what these strings are. Some say they are wisps of cotton thread, probably coming from clothing or bandages. Others say they result from an infectious process in the skin cells." A 2009 Scientific American article noted there's debate about whether it's an infectious disease or psychiatric disorder; a recent CDC study was unable to come to a conclusion as to the illness's cause. (More Joni Mitchell stories.)