Dehydration could be making you more stressed; here’s why

Water is often described as the essence of life and for good reason. From keeping the body energised to supporting the brain, its role in our health goes far beyond just quenching thirst. A recent study by researchers at Liverpool John Moores University has now linked low water intake with a greater stress response, highlighting how hydration may directly affect our mental well-being.

According to the findings, published on 22 August 2025 in the Journal of Applied Physiology, people who drank less than 1.5 litres of fluid a day showed a stress hormone response that was more than 50 percent higher than those meeting their daily hydration needs. Researchers noted that this stronger cortisol reaction was connected to higher risks of depression, diabetes, and heart disease.

So why does water matter so much, and how does it influence our mental state?

From the first living organisms to humans today, survival has always depended on avoiding dehydration. Humans can only live for a few days without it.

round 75 percent of an infant’s body weight and 55 percent of an elderly person’s is made up of water. Every cell and function in the body relies on it. From digestion and circulation to brain activity and energy, hydration underpins it all. Even mild dehydration can result in tiredness, headaches, poor focus, and a decline in both mental and physical performance.

How is hydration linked to stress and mental well-being?

When the body lacks water, levels of the stress hormone cortisol rise, leaving us more anxious, tense, and fatigued. Adequate hydration keeps hormone levels steady, improves blood flow to the brain, and supports neurotransmitters, which together help reduce stress and promote calmness. Drinking enough water can also improve sleep and emotional resilience, two vital tools in coping with everyday pressures.

How does water help the brain?

The brain itself is about 75 percent water. Even slight dehydration can affect concentration, memory, and decision-making. By staying hydrated, the mind remains sharper and less prone to the mental fatigue that often worsens stress.

Can hydration influence mood?

Yes. Studies show that dehydration is linked to irritability, anxiety, and low mood. Meeting your daily water needs helps maintain stable mood regulation by supporting neurotransmitters such as serotonin and dopamine.

Balances stress hormones

Cortisol, the body’s primary stress hormone, rises when hydration levels fall. Drinking enough water helps regulate this hormone, making stress responses more balanced and easier to manage.

Improved sleep

Drinking enough fluid throughout the day, though not too close to bedtime, supports deeper, restorative sleep. In turn, better sleep lowers sensitivity to stress and helps improve emotional balance.

Prevents headaches and tension

Headaches and migraines are common signs of dehydration. These can worsen stress, but drinking enough water reduces their intensity and frequency, keeping stress in check.

What role does hydration play in energy levels?

A lack of water often leads to tiredness, which can magnify stress and reduce our ability to cope. Staying hydrated keeps energy steady and helps prevent feelings of being overwhelmed.

Does it improve our ability to cope with stress?

Proper hydration ensures the brain and muscles receive enough oxygen and nutrients, which allows the body to handle both physical and emotional stressors more effectively.

Help to feel more relaxed

Water regulates body temperature through sweating and circulation. Without enough hydration, discomfort from overheating can cause restlessness and stress. With proper fluid intake, the body feels calmer and more balanced.

Link between hydration and digestion

The gut and brain are closely connected. Dehydration can cause digestive issues like constipation, which can increase stress. Drinking enough water keeps the digestive system moving smoothly, supporting overall comfort and mental ease.

Encourage mindfulness

Taking small breaks to drink water throughout the day can act as mindful pauses. These moments calm the nervous system, reduce stress, and reinforce self-care habits that support mental health.

(This article provides general information only and is not a substitute for professional medical advice. Please consult your doctor or a qualified specialist for guidance.)