If you don’t feel well after a night of poor sleep, you may want to consider dehydration as a cause — not simply the lack of sleep —and drink more water, according to a new study published in the journal SLEEP.

The study found that individuals who slept only six hours at night, rather than the recommended eight, were more likely to be dehydrated.

Dehydration can impact many of the body’s systems and functions, including cognition, mood, physical performance and others. Long term or chronic dehydration can result in more serious issues, such as greater risk of urinary tract infections and kidney stones.

For the study, Pennsylvania State University researchers observed how sleep affected hydration status and risk of dehydration in American and Chinese adults. Participants who reported sleeping six hours had significantly more concentrated urine and 16 to 59 percent higher odds of being inadequately hydrated compared to those who slept eight hours on a regular basis at night.

The cause was tied to how the body’s hormonal system regulates hydration.

The hormone vasopressin is released to help regulate the body’s hydration status. It is released throughout the day, as well as during nighttime sleeping hours, which is what the researchers focused on for this study.

“Vasopressin is released both more quickly and later on in the sleep cycle,” said lead author Dr. Asher Rosinger, assistant professor of biobehavioral health at Penn State. “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.”

Two samples of adults were analyzed through the National Health and Nutrition Examination Survey and one sample was analyzed through the Chinese Kailuan Study. More than 20,000 subjects were included across the three samples.

Participants reported 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 research 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.

In conclusion, the researchers suggest that hydration should be at the forefront of your mind first thing in the morning after a poor night’s sleep.

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

Source: Penn State