'Big' Gong Yoo revealed that he is going through a mental breakdown for not getting any sleep for 3 days.

On the 27th, the website of KBS2 drama 'Big' posted a making video.

In the video, Kang Kyung Joon (Gong Yoo) and Gil Da Ran (Lee Min Jung) are reuniting at the wedding hall in a year.

Gong Yoo and Lee Min Jung displayed a cheerful mood throughout the whole time they were filming. Gong Yoo especially joked around with Lee Min Jung a lot, and cheered her up when she felt tired from the sleep deprivation.

When Lee Min Jung was walking slowly while mumbling, Gong Yoo followed her from the back and explained to the camera, "Mental breakdown. Because she didn't sleep. For 3 days." Gong Yoo, who was in the same condition as Lee Min Jung for not getting sleep for 3 days, still showed cheerful mood that brightened up not only Lee Min Jung but all the other staff members at the filming set.