He said he was "shocked" to receive the diagnosis

The Cry Me A River singer took to Instagram to announce the news that he has been diagnosed with Lyme disease.

The illness is a bacterial infection that spreads to humans through infected ticks, and in some people, symptoms can last for years.

Such symptoms include tiredness, aches, and loss of energy.

He shared the diagnosis on social media after the end of his Forget Tomorrow world tour.

Timberlake explained that he was considering ending the tour early, but decided to persevere.

In a post on Instagram, the music star said: "As many of you know, I'm a pretty private person. But as I'm reflecting on the tour and festival tour - I want to tell you a little bit about what's going on with me.

"Among other things, I've been battling some health issues, and was diagnosed with Lyme disease - which I don't say so you feel bad for me - but to shed some light on what I've been up against behind the scenes.

"If you've experienced this disease or know someone who has - then you're aware: living with this can be relentlessly debilitating, both mentally and physically."

He added, "When I first got the diagnosis, I was shocked for sure. But, at least I could understand why I would be onstage and in a massive amount of nerve pain, or just feeling crazy fatigue or sickness.

"I was faced with a personal decision. Stop touring? Or, keep going and figure it out. I decided the joy that performing brings me far outweighs the fleeting stress my body was feeling.

"I’m so glad I kept going." 

America's Centers for Disease and Control and Prevention says that, if caught early and treated with antibiotics, people can usually recover relatively fast and to complete health.

However, it added that if treated in later stages, some long-term damage may have already been done to the nervous system of joints.

Other famous singers to have struggled with Lyme disease include Justin Bieber, Shania Twain and Avril Lavigne.