Even more evidence has come out showing that not getting enough sleep is linked with an increased risk of obesity.
Research in the American Journal of Human Biology shows that not getting enough shut-eye could affect glucose metabolism and even raise blood pressure. It may also affect how our appetites are regulated, "leading to increased energy consumption," study researcher Dr. Kristen Knutson, of the University of Chicago, said in a statement.
"These findings show that sleeping poorly can increase a person's risk of developing obesity, diabetes, high blood pressure or heart disease," Knutson said in the statement. "Future research should determine whether efforts to improve sleep can also help prevent the development of these diseases or improve the lives of patients with these conditions."
The paper, which draws upon the results of past sleep studies, shows that there is a link between sleeping fewer than six hours a night and having an higher body mass index (BMI), or being obese. The link also seems to be stronger among kids and teens.
Researchers also found that sleep may impact appetite regulation because being sleep deprived has an effect on ghrelin, the appetite hormone, and leptin, which is what gives us the signal to stop eating because we are satiated. Sleep deprivation increases the secretion of ghrelin and leptin, which then may increase how much food we consume.
Just last week, a study was published in the journal Science Translational Medicine showing that sleeping too little or sleeping "against" the body's biological clock increases the risk of becoming obese or developing diabetes.
That study, unlike other sleep studies that are observational or short-term, was controlled -- meaning, people were actually placed in a controlled environment where researchers were able to change how long they slept and the time of day that they slept (similar to what shift workers might experience).
Dr. Richard Simon, M.D., a sleep specialist based in Washington state, told the National Sleep Foundation that compared to our historical counterparts, society today leads a much more sedentary lifestyle -- and that lifestyle, coupled with poor sleep, spells trouble.
"Our levels of physical activity have plummeted, along with our caloric expenditure, yet our caloric intake has not declined. When caloric expenditure declines and caloric intake does not decline, weight gain occurs," Simon told the National Sleep Foundation. "We're also getting less sleep than we used to. ... Add all of those features together, and we have a perfect model for obesity."