Sufficient water intake is important every day, of course, but it’s even more critical to sip when you’re stressed out. “Stress is what we experience when our brain and body try to cope with a challenge, danger, or uncertainty by setting in motion a host of physical response, such as a faster heart rate and soaring adrenaline, to prepare us to take action,” says Laura Lewis Mantell, MD, a physician specializing in pain and stress management, and a personal and professional coach. A faster heart rate and adrenaline rush sets off a stress-cycle in your body that, over time, can be damaging to your health, and is even associated with increased risk for conditions such as diabetes, obesity, and cardiovascular disease.

The relationship between hydration and stress is well documented. Basically, when you’re dehydrated, your body is stressed, and when you’re stressed your brain releases stress hormones, setting off a chain reaction of the stress response in your body. Research from the University of Cincinnati and published in the Journal of Neuroscience concluded that how hydrated you are determines how well your body (and your mind, and therefore emotions and behavior) handles stress. Research published in the World Journal of Psychiatry found that drinking plain water leads to decreased cases of depression and anxiety, both stress-related conditions. “Every single cell in your body requires water to function properly,” says Cynthia Ackrill, MD, fellow of the American Institute of Stress and editor of AIS’s Contentment Magazine. “The brain is 75 to 85 percent water, and even a 2 percent dehydration can result in fatigue, impaired memory, and difficulties with attention and mood.” Dr. Ackrill explains that this relates to stress because “a decrease of 1/2 liter [of water] will increase cortisol levels (a key hormone the body releases when stressed), and long-term cortisol production can lead to adrenal fatigue.” In a cycle of stress and dehydration there is often increased depression and anxiety, leading to more stress to the body. “Water is required to convert tryptophan to serotonin, the natural feel-good chemical,” she adds. Research from 2010, published in journal Human Brain Mapping, found a correlation between dehydration and decreased brain function, suggesting “that prolonged states of reduced water intake may adversely impact executive functions.” On top of that, Dr. Ackrill explains that “the frontal lobe of the brain is the executive center, regulating mood, attention, cognitive function, and all higher process activities—and it’s the most sensitive to stress.” Another large piece of the hydration-stress puzzle is that the body requires water for absorbing nutrients, optimal metabolism, and proper oxygenation. All of these functions are critical for keeping your body and mind working well.

Remember to drink water throughout the day with these tips from the pros:

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