Water, hydration & your mind

Young women who lost about 1.4% of their body weight in water felt lower in mood and energy, more tired and found tasks harder. They also had more headaches and trouble concentrating.

Most thinking tests did not change much. It was how they felt that shifted most.

Young men who lost about 1.6% of their body weight in water felt more tense, anxious and tired. They also made more errors on some attention tasks.

Many studies mix dehydration with heat and hard exercise, and few measure hydration well. That makes it hard to know exactly how much water alone matters.

Drinking water reliably made people feel more alert in studies, even when test scores didn’t change much.

Feeling tired is a common sign of dehydration. Before reaching for another coffee, try a glass of water and see how you feel.

In a trial, people with frequent headaches who drank about 1.5 liters more water a day felt their quality of life improved. Almost half said they felt much better.

But the number of days with moderate headaches didn’t change much. The researchers said it’s reasonable to try for a short time and see.

Other common headache triggers include stress, skipped meals, heavy drinking, poor posture and eyesight problems. A headache diary can help you spot yours.

Call 911 for a headache with

• A seizure
• Confusion
• Numbness or weakness
• A recent head injury
• Sudden, extreme pain

The “8 glasses a day” saying may not suit everyone. U.S. guides suggest about 13 cups of drinks a day for men and 9 for women, but these are general guides, not daily targets.

The NHS suggests about 6 to 8 cups or glasses of fluid a day as a guide.

Coffee and tea count towards your daily fluids. A lot of caffeine may make some people pee more for a short time, but it won’t necessarily dehydrate you.

About 20% of the water we take in comes from foods like fruit and vegetables.

Pale, clear or straw-colored pee usually means you’re drinking enough. Dark yellow, strong-smelling pee is a sign to drink more.

Alcohol makes your body lose more water. Having more than a couple of drinks in a short time raises the risk of dehydration.

• Under 6 months: breast milk or formula only, no extra water
• Ages 1 to 3: about 4 cups of drinks a day
• Ages 4 to 8: about 5 cups a day
• Older children: about 7 to 8 cups a day

Kids may need more when active or in hot, humid weather.

• Add fruit, cucumber or mint to water
• Drink water yourself so kids see it
• Let kids pick a special bottle or cup
• Offer water before they feel thirsty
• Pack water bottles when going out
• Serve water with meals and snacks

Pediatricians say water should be the main drink for kids. Sports drinks have added sugar and are only needed for long, hard exercise or heavy sweating.

Stroke or dementia can affect thirst. People with memory problems may forget to drink, so caregivers should offer drinks often.

Incontinence may lead people to drink less. A gentle, private talk with a provider can help find a plan that works.

• Check whether they’re drinking enough, especially in hot weather
• Keep drinks within easy reach
• Offer drinks often, not just at meals
• Try a simple routine, like a full bottle refilled a few times a day

For moderate work in the heat lasting under 2 hours, drink about 1 cup (8 oz) of water every 15 to 20 minutes. If you sweat for several hours, drinks with electrolytes can help.

In general, don’t drink more than 6 cups an hour. Avoid alcohol and drinks high in caffeine or sugar.

• Ages 9 to 12: about 3 to 8 ounces every 20 minutes during hard exercise
• Teens: about 34 to 50 ounces an hour during activity
• Drinks with electrolytes may be needed if hard exercise lasts over an hour or there’s heavy sweating

Drinking a very large amount in a short time can dilute the salt in your blood. Signs include confusion, nausea, muscle spasms and seizures.

People at higher risk include marathon runners and triathletes, people in extreme heat or doing long, hard exercise, people with kidney problems, and children.

• A glass after brushing your teeth
• A glass when you sit down to work or study
• A glass with each meal
• A sip each time you check your phone

• Fill a big bottle once in the morning
• Keep a glass by your bed and your couch
• Use a straw if it makes drinking easier
• Water-rich snacks like fruit count too

• Add lemon, lime, berries, cucumber or mint
• Freeze fruit in ice cubes
• Try sparkling water or herbal tea
• Use a bottle you like

Shared habits are easier. A water jug on the family table, water breaks at practice, or a refill station at work all make the healthy choice the easy one.