Sandra Bullock battled depression during `Gravity` shoot

Los Angeles: While shooting for space drama `Gravity`, actress Sandra Bullock suffered serious bouts of depression as she was locked in an isolation tank for 10 hours at a time.

The 49-year-old admits the lonely sessions took a serious toll on her mental health, reports

Director Alfonso Cuaron had to keep a close eye on her to ensure she didn`t lose her cool and he used her son, Louis, to cheer her up whenever he felt she needed a boost.

"I was depressed, I was angry, I would get so sad because it was a black room, no human contact, they took away sound... `What they did was, Alfonso could see, because he had cameras always on my face, he would be like, `She`s cracking, she`s cracking, go get the kid`," Bullock said on a talk show.

"They`d created this whole wonderland just outside for Louis (to keep him occupied during filming), so they brought him in," she added.