Not getting enough sleep? Maybe you're drinking too many sugar-sweetened drinks.

Do you find yourself craving sugar-sweetened drinks? Maybe you're not getting enough sleep.

Researchers at the University of California at San Francisco have discovered a connection between sleep deprivation, but they're still not sure whether drinking sugar-sweetened beverages causes people to sleep less, or whether sleep deprivation makes people seek out more sugar and caffeine to stay awake.

“We think there may be a positive feedback loop where sugary drinks and sleep loss reinforce one another, making it harder for people to eliminate their unhealthy sugar habit,” said lead author Aric A. Prather, PhD, assistant professor of psychiatry at UCSF. “This data suggests that improving people’s sleep could potentially help them break out of the cycle and cut down on their sugar intake, which we know to be linked to metabolic disease.”

Both sugary beverage consumption and lack of sleep have been linked – separately – to metabolic syndrome. That's the catch-all phrase doctors use to describe the cluster that includes high blood sugar and excess body fat, which can lead to obesity and type 2 diabetes.

The researchers examined the data to be found in the 2005-2012 records of 18,779 participants in the National Health and Nutrition Survey.

The scientists learned that people who regularly slept five or fewer hours per night also drank 21 percent more caffeinated sugar-sweetened beverages – including both sodas and non-carbonated energy drinks – than those who slept seven to eight hours a night. Thosewho slept six hours per night normally consumed 11 percent more caffeinated sugar-sweetened beverages.

“Short sleepers may seek out caffeinated sugar-sweetened beverages to increase alertness and stave off daytime sleepiness,” Prather said. “However, it’s not clear whether drinking such beverages affects sleep patterns, or if people who don’t sleep much are more driven to consume them. Unfortunately, the data in the current study do not allow us to draw any conclusions about cause and effect.”

One draw back of the data is that the sleep duration figures in the study were based on self-reporting.

Prather concluded that, “Sleeping too little and drinking too many sugary drinks have both been linked to negative metabolic health outcomes, including obesity. Given the likely two-way relationship between sugary drinks and short sleep, enhancing the duration and quality of sleep could be a useful new intervention for improving the health and well-being of people who drink a lot of sugary beverages.”

The research has been published in the journal Sleep Health.