Jang Bum Joon surprised fans with the release of a new single "Can't Sleep". 

Shortly after JTBC's 'Hidden Singer 6' aired on October 23rd, Jang Bum Joon surprised fans with the new single on October 24 at midnight KST. In the description, he wrote "I wrote this song in the shortest time of my music career. Before this song, it was 'Your shampoo scent in the flowers'. The reason behind this is a secret." and thanked 'Hidden Singer 6' panels. 

The song is about unrequited love, but he added "The song could be about past relationships depending on your own experiences, so feel free to interpret it as you wish."

Check out his new song above and watch the latest episode of 'Hidden Singer 6' to find out why he released a new single. How do you like his new song?