While You Were Sleeping (Korean: 당신이 잠든 사이; RR: Dangshini Jamdeun Sai) is a 2011 South Korean television series starring Lee Chang-hoon, Choi Won-young, Oh Yoon-ah and Lee Young-eun.

The daily drama aired on SBS on Mondays to Fridays at 19:15 from May 16 to November 9, 2011 for 120 episodes.

[1] Oh Shin-young (Lee Young-eun) is a hospital cafeteria nutritionist with a bright personality, who is happily married to Yoon Min-joon (Choi Won-young), who works in the sales department of a food company.

But while giving birth, Shin-young falls into a vegetative state induced by the hospital's chief obstetrician Go Hyun-sung (Oh Yoon-ah).

When Hyuk-jin learns of his wife's betrayal, he plans his revenge.