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 femalefirst.co.uk. 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