I’ve been running for over 40 years, and over time, I’ve come to realize something that goes far beyond fitness: hydration and mental health are deeply connected.
Running has always helped me stay sharp—physically and mentally. It’s when my thoughts come together and my energy resets. But a while back, I noticed that something wasn’t quite right. My performance started to dip, sure—but more importantly, I felt mentally off. Foggy. Irritable. Less motivated.
At first, I thought it was just age, or stress, or pushing myself too hard. But then I realized the real issue:
I wasn’t drinking enough water.
Living in Phoenix, Arizona—especially while running 100 miles a month year-round—makes hydration crucial. And I simply wasn’t keeping up. Once I started paying attention, the link became clear. When I’m dehydrated, everything suffers. But when I stay on top of it, everything improves: focus, mood, energy.
This isn’t just a runner’s issue—it’s something that affects everyone. Whether you’re active or not, hydration plays a huge role in how you feel, think, and function.
And there’s actual science behind it.
The Hidden Science of Hydration: What’s Going On Inside?
Hydration doesn’t just affect your muscles—it has a huge impact on your brain and mood too. That’s where biomarkers come in. These are measurable substances in your body that tell a story about what’s happening internally.
Two important ones tied directly to hydration and mood are:
1. Arginine Vasopressin (AVP)
AVP is a hormone your body releases when it senses you’re low on water. It helps your kidneys conserve water and keep your blood pressure steady. But here’s the kicker: high levels of AVP are associated with increased stress, anxiety, and even symptoms of depression.
When you’re dehydrated, your body ramps up AVP—and that can negatively affect your mental well-being, not just your physical performance.
2. Arginine
Arginine is an amino acid involved in nitric oxide production, which helps regulate blood flow and cardiovascular health. It also plays a role in hormone release and immune function. Some research suggests dehydration can reduce plasma arginine levels, which could indirectly affect energy and recovery.
So, if you’re wondering why you feel off or sluggish—even beyond just being thirsty—it could be these internal markers quietly doing their thing.
What You Can Do
Start simple:
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Track your water intake for a week.
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Notice how you feel—physically and mentally—on high-water days vs. low ones.
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Consider wearable devices or apps that track hydration more precisely, if you’re into that kind of thing.
And if you’re a runner, or active in any way, know this: hydration isn’t optional. It’s foundational.
Dig Deeper: Sources and Reading
Here are some recent studies and articles that explain the science behind all this: