When Rest and Water Are Missing: Everyday Stressors That Age the Brain

Most of us know that good sleep and enough water are important. But what if I told you that missing either of these basics doesn’t just make you feel tired or thirsty—it can actually age your body and brain faster?

Two new studies shed light on this hidden cost, and together they reveal something deeper about how our bodies adapt to stress.

The Sleep Study: Restless Nights, Older Brains

A large study of over 27,000 adults from the UK Biobank found that people with poor sleep habits—like short or long sleep duration, insomnia, snoring, or daytime sleepiness—had brains that looked up to a year older than their chronological age.

This wasn’t just about feeling foggy. Their brains were literally showing signs of accelerated ageing on MRI scans. And here’s the key: a significant part of this effect was explained by chronic low-grade inflammation. Poor sleep puts the brain into a constant state of “defense mode” instead of recovery.

The Dehydration Link: A Body on High Alert

We recently discussed another study showing how chronic dehydration stresses the body. When water is lacking, the body activates hormonal systems to hold on to salt and fluids. This persistent alarm drains bioenergetic resources and forces the body into costly trade-offs, leaving less energy for repair, immune balance, and long-term resilience.

Just like poor sleep, dehydration leaves the body stuck in adaptation without resolution—a cycle that keeps stress hormones high and inflammation smoldering.

The ERM Perspective: Everyday Stressors, Hidden Costs

Both sleep loss and dehydration are examples of what we call Exposure-Related Malnutrition (ERM). ERM describes how ongoing stressors—whether from lifestyle, environment, or diet—push the body into persistent maladaptation:

• Energy is diverted to short-term survival systems.

• Recovery and re-anabolism (building back stronger) are delayed.

• Chronic low-grade inflammation becomes the “new normal.”

• Over time, tissues—including the brain—show signs of premature ageing.

In other words, your body isn’t broken—it’s exhausted. Stuck in adaptation. And that exhaustion shows up as inflammation, fatigue, and, as the sleep study demonstrates, even a brain that looks older than its years.

What This Means for You

The hopeful message is that both sleep and hydration are modifiable stressors. Just as poor sleep and dehydration accelerate biological wear-and-tear, restoring them can support resilience and slow down ageing.

• Aim for 7–8 hours of quality sleep, with regular rhythms.

• Keep hydrated through the day, not just when you feel thirsty.

• Remember: these are not luxuries. They are the foundations of your body’s ability to recover and rebuild.

Final Thought

We often think about ageing as something written in our genes. But these studies remind us that everyday choices—like whether we drink enough water or get a good night’s sleep—can tip the balance between adaptation and exhaustion.

Your body wants to recover. Give it the basics, and it will thank you with resilience that lasts.

Miao, Y., Wang, J., Li, X., Guo, J., Ekblom, M. M., Sindi, S., Zhang, Q., & Dove, A. (2025). Poor sleep health is associated with older brain age: The role of systemic inflammation. eBioMedicine, 105941. https://doi.org/10.1016/j.ebiom.2025.105941

Kashi, D. S., Hunter, M., Edwards, J. P., Zemdegs, J., Lourenço, J., Mille, A.-C., Perrier, E. T., Dolci, A., & Walsh, N. P. (2025). Habitual fluid intake and hydration status influence cortisol reactivity to acute psychosocial stress. Journal of Applied Physiology, 139(3), 698–708. https://doi.org/10.1152/japplphysiol.00408.2025