A shorter sleep can lead to dehydration

According to a Penn State study, adults who sleep just 6 hours a night, compared with 8, are more likely to become dehydrated.

These findings suggest that those who do not feel well after a bad night's sleep may want to consider dehydration – not just bad sleep – as a cause and drink more water.

The results of the study are published in the journal TO SLEEP November 5th

The researchers studied the impact of sleep on the state of hydration and the risk of dehydration in American and Chinese adults. In both populations, adults who reported sleeping 6 hours had significantly more concentrated urine and an increased probability of hydration of 16% to 59% higher than adults sleeping regularly 8 hours a night.

The cause was related to how the body's hormonal system regulates hydration.

A hormone called vasopressin is released to help regulate the body's hydration status. It is broadcast throughout the day, as well as during the night, what the researchers focused on for this study.

"Vasopressin is released more quickly and later in the sleep cycle," says lead author Asher Rosinger, MPH, PhD, an assistant professor of biological health at Penn State, in a statement. "So, if you wake up earlier, you may miss that window in which a greater amount of hormone is released, disrupting the body's hydration."

Dehydration negatively affects many body systems and functions, including cognition, mood, physical performance, and others. Chronic or long-term dehydration can lead to more serious problems, such as an increased risk of urinary tract infections and kidney stones.

"If you only sleep six hours a night, it can affect your hydration state," Rosinger says. "This study suggests that if you do not get enough sleep and feel sick or tired the next day, drink more water."

Two samples of adults were analyzed as part of the National Health and Nutrition Survey and a sample of adults was analyzed as part of the Chinese Kailuan study. More than 20,000 adults were included in all three samples. Participants were asked about their sleep patterns and also provided urine samples that were analyzed by researchers looking for biomarkers of hydration.

All data are cross-sectional observations and studies or a cross-sectional wave of a cohort study; therefore, the results of the association should not be considered causal. Future studies should use the same methodology for all sites and examine this relationship longitudinally over a week to understand the baseline state of sleep and hydration, Rosinger says.