Stressed? It Could Be a Sign You're Not Drinking Enough Water

• Hydration was isolated as the key stress variable — To determine whether water intake alone could influence stress responses, researchers controlled for sleep quality, psychological traits, and perceived stress. The participants were healthy, aged 18 to 35, non-smokers, and free from immune, cardiovascular, metabolic, or sleep disorders. Those who consumed excessive caffeine or alcohol were excluded.³

• Participants were divided into LOW and HIGH fluid intake groups — Using national fluid intake data, researchers identified individuals with the lowest and highest daily water consumption. The LOW group drank less than 1.5 liters per day, while the HIGH group met recommended intakes (2 liters for women and 2.5 liters for men). Each group had 16 participants matched for age, gender, sleep quality, and anxiety levels.⁴

• Hydration levels were tracked before a stress simulation — For seven days, participants recorded their fluid intake using smart bottles. On the eighth day, they underwent the Trier Social Stress Test (TSST), which simulates real-world stress through public speaking and mental arithmetic.

Hydration was assessed using urine concentration and color, as well as checking blood levels of copeptin (a hormone that helps regulate water balance and blood volume). The LOW group consistently showed darker urine, higher urine concentration, and elevated copeptin, which are clear signs of dehydration.^5,6

• Cortisol spikes were significantly higher in the low-fluid group — Saliva samples taken after the TSST also revealed that levels of cortisol, the stress hormone, were 50% higher in the LOW group. Both groups experienced similar increases in heart rate and anxiety, but only the LOW group showed a significant increase in cortisol.^7,8

• Thirst did not reflect actual hydration status — Despite similar thirst ratings and blood concentration levels, the LOW group had more concentrated urine and exaggerated cortisol responses. This shows that thirst is not always a reliable indicator of hydration.⁹

• Poor hydration may increase long-term health risks — The study concluded that the exaggerated cortisol reactivity seen in the LOW group is associated with poor hydration and may contribute to long-term health problems. Chronic low fluid intake has also been linked to higher risks of metabolic, renal, and cardiovascular disease.¹⁰

• The study’s weeklong design added real-world credibility — Unlike one-time observational studies, this research prospectively monitored participants for seven days while they maintained their usual drinking habits. This allowed researchers to observe how consistent hydration patterns influenced stress hormone responses, rather than relying on short-term or artificial changes.¹¹

• Vasopressin protects circulation when fluid is low — During dehydration, vasopressin signals your kidneys to conserve water and constricts blood vessels to raise blood pressure. This helps maintain blood flow to vital organs like the brain and heart, especially during heat, exertion, or emotional stress. It’s a survival mechanism — but over time, it can strain your cardiovascular system.¹³

• Vasopressin helps trigger cortisol — When you’re stressed or dehydrated, vasopressin sends signals to your brain that lead to cortisol release. Cortisol helps your body stay alert and manage pressure, but too much of it, especially when triggered silently by dehydration, can wear down your heart, kidneys, and nerves over time.¹⁴

• Too much or too little vasopressin disrupts your health — If your body produces too much vasopressin, you may retain excess water and dilute your blood. Too little or poor kidney response leads to dehydration and electrolyte imbalance. Both extremes may strain your heart, kidneys, and nervous system, especially during periods of stress.¹⁵

• Low hydration reduces blood flow to the brain — When you’re dehydrated, your blood becomes thicker and flows more slowly. This means less oxygen and nutrients reach your brain, which leads to fatigue and slower reaction times.¹⁷

• Your brain shrinks and slows down — Magnetic resonance imaging (MRI) scans show that even slight dehydration causes brain cells to contract. This shrinkage affects memory, decision-making, and overall mental clarity. In older adults, long-term dehydration is linked to reduced brain mass and volume, both markers of faster aging in the brain.¹⁸

• Mood-regulating chemicals become less effective — Dehydration affects how your brain uses serotonin and dopamine, which help regulate mood, motivation, and emotional stability. When they’re disrupted, you may feel anxious, irritable, or mentally drained.¹⁹

• Chronic dehydration may quietly accelerate aging — A 25-year study from the National Institutes of Health analyzed data from the Atherosclerosis Risk in Communities study, which followed 15,792 adults. Researchers found that serum sodium levels above 142 milliequivalents per liter (mEq/L) increased chronic disease risk by 39%, and levels above 144 milliequivalents per liter raised mortality risk by 21%.

People with sodium levels outside the ideal range were also 10% to 15% more likely to be biologically older than their actual age. As study author Natalia Dmitrieva, Ph.D., explained:²⁰

“Decreased body water content is the most common factor that increases serum sodium, which is why the results suggest that staying well hydrated may slow down the aging process and prevent or delay chronic disease.”

• Urine color and odor reflect hydration and mineral balance — Use your urine as a visual guide to assess hydration throughout the day. Healthy urine should be pale straw or light yellow. If it appears dark yellow or amber and carries a strong odor, it likely signals dehydration. This odor intensifies when waste compounds become concentrated due to insufficient water intake.

• Sugar cravings and constipation can be signs of dehydration as well — When your body lacks water, digestion slows down. You might crave sugary foods for quick energy, and bowel movements can become difficult because water helps move waste through your intestines.

• Your body sends signals before thirst kicks in — Dry mouth, fatigue,²¹ headaches, and confusion are early signs your body is low on water. These symptoms show up before you feel thirsty, making dehydration easy to miss. Other symptoms to take note of are:

Mild to moderate dehydration

Severe dehydration

• Hydration works best when paired with electrolytes — Natural salts like Himalayan pink salt, Celtic sea salt, and Mediterranean Sea salt support fluid balance without the contaminants found in processed table salt. If you’re sweating heavily or drinking large amounts of water, add a pinch of salt and a splash of lemon or organic juice to improve absorption.

You can also hydrate through foods like watermelon, cooked vegetables, coconut water, raw milk, and herbal teas. These are all rich in minerals and natural sugars that help water enter your cells.

• Support structured water inside your cells — Your body doesn’t just use liquid water — it also relies on a gel-like form called structured water, or exclusion zone (EZ) water. This type of water exists inside your cells and helps maintain their shape and function.

You can increase structured water by eating well-cooked leafy greens and exposing your skin to sunlight, especially near-infrared and UV light. These practices help your body build and maintain hydration from the inside out.

• Balance sodium and potassium for heart and heat health — A healthy sodium-to-potassium ratio is key for blood pressure regulation, heart function, and heat resilience. Processed foods tend to be high in sodium and low in potassium, which throws this ratio off. Focus on whole foods like bananas, sweet potatoes, and leafy greens to restore balance. I explore this further in my article, “Surprise! Everything You’ve Been Told About Salt Is Wrong.”

• Stay safe during extreme heat — Hydration is only part of the equation. To protect yourself during hot weather, avoid sugary sodas and sports drinks — they worsen dehydration and strain your kidneys. Wear breathable, light-colored clothing, limit strenuous activity during peak heat, and use fans and cooling compresses or take cold showers to regulate body temperature.²²