Healthbeat: The Sleep Diet

If you want to lose weight, the answer might be getting more sleep.

About 35 percent of adults report getting less than seven hours of sleep a night, which can cause daytime drowsiness, irritability, and weight gain.

In a recent study, scientists found that too little sleep can affect the balance of bacteria in your gut. Researchers also believe that too little sleep can affect hormones that regulate hunger. Other studies have suggested that less sleep can slow your metabolism.

Another theory suggests that tired people are less likely to be active.

In one of the largest studies to date, women who slept five hours or less a night were 15 percent more likely to become obese compared with those who slept seven hours.

Another study found that people who slept five and a half hours per night consumed about 385 more calories a day than those who slept seven hours or more.

"There are guidelines to follow, and you have to look at both quantity and quality of sleep," said Kathleen Armstrong, PhD, of the University of South Florida.

Aim for seven to nine hours of sleep per night. To help you meet that goal, go to bed and wake up at the same time every day, even on weekends. It also helps to keep your bedroom between 60 and 67 degrees and to replace your mattress after about nine years of use.