Too little sleep can cause dehydration, study finds

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If you sometimes don’t feel well after sleeping only six hours, you may need more than just a few more hours sleep. You may also need to drink more water.

That’s according to a study by researchers at Penn State, who found that not getting enough sleep can leave you inadequately hydrated. It all has to do with the way the body’s hormonal system regulates hydration. A hormone called vasopressin is released to help regulate the body’s hydration status. It is released throughout the day, as well as during nighttime sleeping hours.

“Vasopressin is released both more quickly and later on in the sleep cycle,” said Asher Rosinger, assistant professor of biobehavioral health at Penn State, in a news release. “So, if you’re waking up earlier, you might miss that window in which more of the hormone is released, causing a disruption in the body’s hydration.”

Dehydration is a lot more than just being thirsty. It negatively affects many of the body’s systems and functions, including cognition, mood, physical performance and others. Long term or chronic dehydration can lead to more serious problems, such as higher risk of urinary tract infections and kidney stones.


“If you are only getting six hours of sleep a night, it can affect your hydration status,” Rosinger said. “This study suggests that if you’re not getting enough sleep, and you feel bad or tired the next day, drink extra water.”

About the study

In conducting the study, researchers looked at how sleep affected hydration status and risk of dehydration in U.S. and Chinese adults. In both populations, adults who reported sleeping six hours had significantly more concentrated urine and 16-59 percent higher odds of being inadequately hydrated compared to adults who slept eight hours on a regular basis at night.

Two samples of adults were analyzed through the National Health and Nutrition Examination Survey and one sample of adults was analyzed through the Chinese Kailuan Study. More than 20,000 adults were included across the three samples. Participants were surveyed about their sleeping habits, and also provided urine samples which were analyzed by researchers for biomarkers of hydration.

All data is observational and from cross-sectional studies or a cross-sectional wave of a cohort study; therefore, the association results should not be viewed as causal. Future studies should use the same methodology across sites and examine this relationship longitudinally over the course of a week to understand baseline sleep and hydration status, Rosinger said.

Results of the study were published in the journal SLEEP on Nov. 5.

About the Author

Truman Lewis
Truman has been a bureau chief and correspondent in D.C., Los Angeles, Phoenix and elsewhere, reporting for radio, television, print and news services, for more than 30 years. Most recently, he has reported extensively on health and consumer issues for ConsumerAffairs.com and FairfaxNews.com.