It turns out that what parents have been telling kids for ages is actually true: you need your sleep to stay healthy.

A new study led by a University of California San Francisco sleep researcher found that people who sleep six hours a night or less are four times more likely to catch a cold when exposed to the virus, compared to those who spend more than seven hours a night in slumber land.

his is the first study to use objective sleep measures to connect people’s natural sleep habits and their risk of getting sick, according to Aric Prather, PhD, assistant professor of Psychiatry at UCSF and lead author of the study. The findings add to the growing evidence of the importance of sleep for our health, he said:

“Short sleep was more important than any other factor in predicting subjects' likelihood of catching cold. It didn’t matter how old people were, their stress levels, their race, education or income. It didn’t matter if they were a smoker. With all those things taken into account, statistically sleep still carried the day.”

Public Health Epidemic

The Centers for Disease Control and Prevention have called insufficient sleep a public health epidemic, linking poor sleep with car crashes, industrial disasters and medical errors. According to a 2013 survey by the National Sleep Foundation, one in five Americans gets less than six hours of sleep on the average work night, the worst of the six countries surveyed.

To understand how sleep affects the body’s response to a real infection, Prather collaborated with Carnegie Mellon psychologist Sheldon Cohen, PhD, the study’s senior author, who has spent years exploring psychological and social factors contributing to illness.

Cohen’s group gives volunteers the common cold virus to safely test how these various factors affect the body’s ability to fight off disease.

For this paper, Prather approached Cohen about investigating sleep and cold susceptibility using data collected in his lab’s recent study, in which participants wore sensors to get hard data about sleep.

Beyond Groggy

They found that subjects who had slept less than six hours a night the week before were 4.2 times more likely to catch the cold compared to those who got more than seven hours of sleep, and those who slept less than five hours were 4.5 times more likely.

“It goes beyond feeling groggy or irritable,” Prather said. “Not getting sleep fundamentally affects your physical health."

The study shows the risks of chronic sleep loss better than typical experiments in which researchers artificially deprive subjects of sleep, said Prather, because it is based on subjects' normal sleep behavior.

This study adds yet another piece of evidence that sleep should be treated as a crucial pillar of public health, along with diet and exercise, the researchers said. But it’s still a challenge to convince people to get more sleep, especially if you are a parent of a young child.

Aric A. Prather, Denise Janicki-Deverts, Martica H. Hall, Sheldon Cohen. Behaviorally Assessed Sleep and Susceptibility to the Common Cold. SLEEP, 2015; DOI: 10.5665/sleep.4968

For future updates, subscribe via Newsletter here or Twitter