I have been told that it isn't enough to just drink water to get yourself hydrated.. you have to change the electrolyte make up. Which means salt and sugar.

Important Functions of Sugar in the Body

"1. Absorption of water and other nutrients – Glucose, also known as dextrose, is the most common form of sugar and what is used in the body for energy. Glucose enhances sodium and water transport across the upper intestinal wall and into the bloodstream (a process more commonly known as osmosis). In other words, a solution of water + glucose + salt hydrates better than water alone."