Many people claim that if you don’t stay hydrated throughout the day, your energy levels and brain function start to suffer.

There are plenty of studies to support this.

One study in women showed that a fluid loss of 1.36 percent after exercise impaired mood and concentration and increased the frequency of headaches.

Another study in China that followed 12 men in university found that not drinking water for 36 hours had noticeable effects on fatigue, attention and focus, reaction speed, and short-term memory.

Even mild dehydration can reduce physical performance. A clinical study on older, healthy men reported that just a 1 percent loss of body water reduced their muscle strength, power, and endurance.

Losing 1 percent of body weight might not seem like a lot, but it’s a significant amount of water to lose. This usually happens when you’re sweating a lot or in a very warm room and not drinking enough water.

Mild dehydration caused by exercise or heat can have negative effects on both your physical and mental performance.

At the end of the day, no one can tell you exactly how much water you need. This depends on many factors.

Try experimenting to see what works best for you. Some people may function better with more water than usual, while for others it only results in more frequent trips to the bathroom.

If you want to keep things simple, these guidelines should apply to the majority of people:

1. Drink often enough throughout the day for clear, pale urine.
2. When you’re thirsty, drink.
3. During high heat and exercise and other mentioned indications, make sure to drink enough to compensate for the lost or extra needed fluids.

That’s it!