Even mild dehydration may affect our moods and ability to concentrate. In a new study of 25 healthy women, mild dehydration dampened moods, increased fatigue, and led to headaches.

The women in the study had an average age of 23. They were not superbly fit, nor couch potatoes.

Each woman was tested after treadmill exercise and again after treadmill exercise plus a diuretic pill, which was designed to force dehydration (urine loss).

The women were given a battery of tests measuring their concentration, memory, and mood when they were dehydrated and when they were not.

Overall, women’s mental ability was not affected by mild dehydration. But they did feel the tasks were more difficult. They reported more fatigue and felt down.

This was similar to earlier results from the same researchers in a dehydration study on men.

But “women were more fatigued and this was true during mild exercise and when sitting at a computer,” says researcher Lawrence E. Armstrong, PhD. He is a professor of environmental and exercise physiology at the University of Connecticut’s Human Performance Laboratory in Storrs, Conn.

The findings appear in The Journal of Nutrition, Jan 2012.

The message is clear: think about hydration and take regular steps to prevent it. That means drinking fluids with meals and between meals.

Take special care to drink extra if you are exerting yourself and, of course, in hot weather.

How Much?

Forget the 6 – 8 glasses a day nonsense. That’s a typical hoax that “everybody knows”. It’s dangerous and will stress your kidneys. People with even mild heart failure should be particularly careful.

The correct way to gauge your fluid levels is to watch the color of your urine; it should be clear or just mildly yellow. If you have dark urine, you are way under-hydrated.

There is also another cute test you can do:

Put your hand palm down on your lap and watch the veins distend. They should stick out clearly on the back of your hand.

Now raise your hand slowly up to head height and watch the veins. When they collapse will tell you how hydrated you are. If by chest height your veins start to disappear, you are dehydrated. If your hand goes up to eye level without collapsing, you are OK for fluid.

Neat huh?