The Stress-Hydration Connection: How Less Water Elevates Your Stress Response

Drinking less than the recommended amount of water may increase your stress response, according to a new study from scientists at Liverpool John Moores University in the UK. The study, published in the Journal of Applied Physiology, found that people who drank less than 1.5 liters of fluid per day had a cortisol response to stress that was more than 50% higher than those who met the daily fluid recommendations.

Cortisol is the body's main stress hormone. A higher cortisol response to stress has been linked to an increased risk of heart disease, diabetes, and depression.

To understand this link, researchers divided healthy young adults into two groups:

• A "low-fluid" group who drank less than 1.5 liters of fluid daily.
• The high-fluid group was comprised of individuals who met the daily fluid intake recommendations (2 liters for women and 2.5 liters for men).

After a week of maintaining their usual drinking habits, participants underwent a simulated stressful event. While both groups reported similar feelings of anxiety and had similar increases in heart rate, only the low-fluid group showed a significant jump in their cortisol levels. The low-fluid group also had darker, more concentrated urine, a sign of poor hydration.

The body's water-regulation system is the key. When you become dehydrated, it triggers the release of a hormone called vasopressin. While vasopressin's main job is to help the kidneys retain water, it also acts on the brain's stress center, which can lead to an increase in cortisol. This means that a lack of proper hydration can directly contribute to a higher stress response.

The study suggests that staying hydrated may help your body handle stress more effectively. To check if you're hydrated, simply look at the color of your urine—it should be a light yellow. The findings support current recommendations for daily fluid intake: about 2 liters for women and 2.5 liters for men.

If you know you have a stressful day or event coming up, keeping a water bottle nearby could be a simple habit with potential long-term health benefits.