Not drinking enough water can fuel your stress, anxiety and long-term health risks; says study

Dehydration doesn't just drain your body, it can heighten stress, worsen anxiety, and put your long-term health at risk.(Image: Pexels)

Forgetting to carry your water bottle may seem like a trivial thing. But new science suggests that skipping out on your daily fluids could cause a spike in stress levels and harm your health.

Researchers at Liverpool John Moores University have found a startling link between dehydration and a spike in cortisol, the body’s main stress hormone. During the study the participants didn’t even feel thirstier. The study from LJMU has found that people who drink less than 1.5 litres of fluid a day—about seven cups of tea—showed cortisol levels over 50% higher during stressful situations.

It’s a stress surge with serious consequences. Cortisol, while essential in short bursts, is linked with long-term health conditions like heart disease, depression, and even diabetes when chronically elevated. Also, poor hydration didn’t make people feel thirstier. But their body was absolutely feeling the strain.

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As per the research, the underhydrated participants didn’t report more thirst—but lab tests results were shocking. Darker, more concentrated urine, along with increased cortisol, were the biological giveaways. This was due to vasopressin, a hormone triggered when you're dehydrated. Vasopressin tells your kidneys to hang on to water, but it also activates the stress response in your brain. As a result, more stress hormone circulates, even if you feel totally fine, until you’re not.

6 reasons staying hydrated helps your stress levels and health

• Cortisol control starts with your water bottle: Hydration helps blunt the body's exaggerated cortisol response during stress. Keep your stress hormone in check with steady sips throughout the day.

• Your body can feel stress even if you don’t: The study shows that even when people felt equally anxious, the underhydrated group’s bodies responded more strongly. Trust your biology, not your perception.

• Vasopressin may cause harm: This hormone helps the body conserve water but also increases stress signalling. Dehydration fuels this loop further.

• You don’t have to feel thirsty to be dehydrated: Thirst is a late signal. By the time you feel parched, your body’s already compensating hard behind the scenes.

• Dehydration strains kidneys and the brain’s stress centre: The kidneys work overtime to manage fluid balance, while the hypothalamus (your stress HQ) fires off cortisol. It’s a high-stakes internal juggle.

• Hydration is a simple, science-backed stress hack: No fancy wellness products needed. Just aim for 2L of fluid a day (2.5L for men). Check your urine: light yellow suggests you are good.