Study of the Day: Mild Dehydration Alters Mood, Makes Thinking Hard

Even if you're not yet thirsty, a lack of water may be affecting your disposition, energy level, and ability to concentrate, according to a new study.

main puhhha shutterstock_92054753.jpg

PROBLEM: Most people only drink water when they're thirsty. But what if even just mild dehydration, defined as approximately 1.5 percent loss in normal water volume, can already cause our minds and bodies to underperform?

METHODOLOGY: Researchers at the University of Connecticut's Human Performance Laboratory recruited 25 young, healthy women who exercised for less than an hour a day. The participants were hydrated the night before each of the three evaluations where they were tasked to walk on a treadmill to induce dehydration. They were also put through a battery of cognitive experiments that measured vigilance, concentration, reaction time, learning, memory, and reasoning. Their scores were then compared against a separate series of tests when the individuals were not dehydrated.

RESULTS: Lack of water caused headaches, fatigue, and difficulty in concentrating. The women also perceived the cognitive tasks as more difficult when slightly dehydrated, even though there was no significant reduction in their ability to think. Another study involving men showed similar adverse effects.

CONCLUSION: Mild dehydration can alter a person's mood, energy level, and ability to think clearly.

IMPLICATION: Relying on thirst as a cue to drink up may be inadequate. Study co-author and physiology professor Lawrence E. Armstrong says in a statement that, by the time this sensation kicks in, dehydration may already be affecting how our mind and body perform.

SOURCE: The full study, "Mild Dehydration Affects Mood in Healthy Young Women," is published in The Journal of Nutrition.

Image: puhhha/Shutterstock.

Presented by

Hans Villarica writes for and produces The Atlantic's Health channel. His work has appeared in TIME, People Asia, and Fast Company.

Saving the Bees

Honeybees contribute more than $15 billion to the U.S. economy. A short documentary considers how desperate beekeepers are trying to keep their hives alive.

Join the Discussion

After you comment, click Post. If you’re not already logged in you will be asked to log in or register.

blog comments powered by Disqus

Video

How to Cook Spaghetti Squash (and Why)

Cooking for yourself is one of the surest ways to eat well.

Video

Before Tinder, a Tree

Looking for your soulmate? Write a letter to the "Bridegroom's Oak" in Germany.

Video

The Health Benefits of Going Outside

People spend too much time indoors. One solution: ecotherapy.

Video

Where High Tech Meets the 1950s

Why did Green Bank, West Virginia, ban wireless signals? For science.

Video

Yes, Quidditch Is Real

How J.K. Rowling's magical sport spread from Hogwarts to college campuses

Video

Would You Live in a Treehouse?

A treehouse can be an ideal office space, vacation rental, and way of reconnecting with your youth.

More in Health

Just In