LOS ANGELES — Justin Timberlake has been diagnosed with Lyme disease, the former NSYNC star said on Instagram Thursday. Timberlake shared the news in a post commemorating his Forget Tomorrow tour, which wrapped in Turkey on Wednesday, adding that the disease “can be relentlessly debilitating, both mentally and physically.”

A family source tells PEOPLE that the Grammy winner's diagnosis has "brought clarity to a series of unexplained issues" as Biel has been "incredibly supportive"

Chris Kirkpatrick took to Instagram to shower praise on Timberlake, who revealed Thursday that he was diagnosed with the debilitating disease.