New research by charity Scope says 38 percent of us do it, but why?

Emily Shanahan hid her Asperger’s and dyspraxia because she was being bullied at school. The London 2012 Paralympics helped her feel more positive about her impairments, and support dog Magic has given her confidence. Emily spoke to Emma Tracey.

Watch here: http://www.bbc.co.uk/programmes/p048291q