Hydration has a major effect on brain function and energy levels. Studies show that even mild dehydration - 1-3% of body weight - can impair many aspects of brain function.
"In a study in young women, researchers found that fluid loss of 1.4% after exercise impaired both mood and concentration. It also increased the frequency of headaches.
Many members of this same research team conducted a similar study in young men. They found that fluid loss of 1.6% was detrimental to working memory and increased feelings of anxiety and fatigue."
The brain needs water to manufacture hormones (molecules produced by the endocrine system that send messages to help regulate body processes) and neurotransmitters that transmit signals from nerve cells to muscles, glands, or other nerves. Neurotransmitters regulate many necessary functions, including heart rate.
Dehydration affects sodium and electrolyte levels in the body, which have also been linked to cognitive changes.
The upshot: To guarantee peak performance, mentally and physically, it's crucial to hydrate!