You already know you should be getting seven to nine hours of shut-eye a night. But are you? Probably not. According to the Centers for Disease Control and Prevention, 30 percent of employed U.S. adults clock less than that and the results aren't pretty. Not only does lack of sleep hamper long-term productivity, but it can also ravage your skin and your sex drive.

Fortunately, Dr. Mathias Basner of the University of Pennsylvania Perelman School of Medicine may have a solution. After analyzing the sleep and work habits of 124,517 American adults, as recorded in the American Time Use Surveys from 2003 to 2011, he and his colleagues determined that all you need to do is start your day later, or at least make the start time more flexible. The research was published online in the journal Sleep.

"Results show that with every hour that work or educational training started later in the morning, sleep time increased by 20 minutes," explains the research release. "Respondents slept an average of only six hours when starting work before or at 6 a.m. and 7.29 hours when starting work between 9 a.m. and 10 a.m." Self-employed respondents fared even better, obtaining "significantly more sleep than private sector employees" and becoming 17 percent less likely "to be a short sleeper."

Clearly, flexible schedules could make people feel better at work, though not everyone's convinced of their merit. Allowing team members some wiggle room in when (and where) they work has proved to help attract and retain top talent. But that doesn't mean much if senior leadership isn't involved in the effort, according to research firm Mercer.

A study published in the Academy of Management Journal offers a reason: "Managers often interpret a person's use of flex work options as a signal of high or low job commitment," writes Time's Nanette Fondas. Specifically, "if a boss attributes an employee's need for flex to personal-life reasons like child care, as opposed to job performance-enhancement reasons like acquiring new skills, the boss tends to assess the employee as less committed and less deserving of career rewards such as raises and promotions."