A foggy head is not always a sleep problem, a motivation problem, or a sign that the day has gone off track. Sometimes, it is much simpler: the brain is running low on water. Water is easy to overlook because it feels ordinary. It does not have the drama of caffeine, the promise of a supplement, or the comfort of a favorite snack. Yet every thought, memory, decision, and reaction depends on a steady internal balance of fluid. When that balance slips, the brain often notices b