From ScienceDaily:

Not drinking enough water could intensify stress responses. Researchers found that under-hydrated individuals had cortisol levels more than 50% higher during stressful situations. Poor hydration didn’t make participants feel thirstier, but it did trigger biological signs of strain. Keeping a water bottle handy could help manage stress and safeguard health.

Bobby Boucher in The Waterboy. He's in an orange jersey is making an awkward facial expression and looking off screen.