What should I know about hydration

Aim for steady fluid intake across the day, adjusting for exercise, heat, sweating, and sleep needs.

• Baseline: A practical starting point is about 8 oz (240 ml) of fluid per hour for the first 10 hours after waking—roughly 2.4 liters total. Treat this as a flexible guide, not a requirement to drink on the hour. 1
• Exercise: The Galpin equation suggests body weight in pounds divided by 30, in ounces, every 15–20 minutes of exercise. In heat or with heavy sweating, increase that amount by about 50%–100%. 2 3
• How to drink: Sip or drink at a comfortable, regular pace rather than forcing large amounts at once; slower, steadier intake can help avoid gastrointestinal distress. 4
• Why it matters: Adequate hydration can support alertness, focus, energy, and physical performance; even mild dehydration may contribute to fatigue or brain fog. 5
• Sleep and food: If nighttime bathroom trips disturb your sleep, hydrate adequately during the day and reduce fluid intake later in the evening, sipping as needed. Water-rich foods such as fruit also contribute to hydration. 6 7