According to a survey of 2,000 working Americans by fitness and nutrition app Freeletics, respondents said they had about 60 "bad days" a year. That's two months a year! The cause of those bad days? The number one reason was lack of sleep, with 67 percent saying not getting enough sleep made them miserable all day. The other big cause was work stress. 80 percent of respondents said their bad days were made even worse, in part, by work-related stress. 50 percent of respondents said they were more likely to eat unhealthy foods after a bad day, and 34 percent said that they were more likely to drink alcohol.