Sports Drinks such as Gatorade are good for hydration to keep you hydrated and to hydrate your body when you become dehydrated.
The Gatorade and other sports drinks contain electrolytes including sodium and potassium which is important to replace when you lose those electrolytes when you get dehydrated.
Of course water is the best hydration drink and you should drink plenty of water even when you're not thirty to prevent dehydration in the first place.
Dehydration can be very serious and could cause death or a hospital stay so always stay hydrated.