days, in individuals who sleep less than six hours a night. >> reporter: and lack of sleep makes workers less productive. >> if the people who slept less than six hours a night simply upped the game a little bit, that would save $200 billion a year in lost productivity. >> reporter: lack of sleep causes accidents and is linked to heart disease, diabetes, and depression. risk of death increases 13% for people who average less than six hours a night, compared to those getting seven to nine. do you have to change the n lture so that if you get an e- mail at 11 p.m. and you don't answer it, it's okay? >> yes. and even more, i have to not send them. >> reporter: powering up by powering down. dr. jon lapook, cbs news, new york. >> mason: and now you know the story of rest. that's the cbs evening news. scott will be back tomorrow. i'm anthony mason. thanks for watching. good night. captioning sponsored by cbs captioned by media access group at wgbh access.wgbh.org