When it comes to hydration, most people don’t think about preventing fluid and electrolyte imbalances. They merely think about drinking enough water.

This message has been drilled into our minds since childhood. To stay healthy, drink an 8 oz glass of water, 8 times per day. The problem is, there never was any science supporting this 8×8 rule. The real origin of this flaky myth is fairly pedestrian, and in fact the science indicates that drinking to thirst is sufficient in most circumstances.

In actuality, drinking too much plain water can dilute blood sodium, sometimes to dangerously low levels. The clearest example of this is the unfortunate marathon runners who experience confusion, light sensitivity, and even seizures at the finish line. These aren’t symptoms of fatigue, or even dehydration – they’re symptoms of overhydration.

Specifically, they’re indicative of exercise-associated hyponatremia. While hyponatremia is an electrolyte imbalance, it’s often treated as dehydration because the symptoms look similar. Yet drinking more water only worsens the condition. This isn’t just affecting elite athletes. Proper hydration can help all of us feel and perform our best, and that means dialing in fluid balance – so let’s start there.