Do you get cramps in your legs at night...especially when you are sleeping?

This could be from an imbalance in your calcium/magnesium and possibly potassium/sodium ratio.  These minerals and electrolytes are very important in muscle relaxation and contraction and also for regulating heart rate.

If you get cramps in your legs at night or early morning, try taking 200-400 mg of magnesium at night before bed.  Also eat some bananas and celery during the day to increase your potassium.

Electrolyte drinks would also be beneficial to help with energy during the day and balance out your mineral levels.  This is especially important to do during this hot weather. 

So...

Drink plenty of water, add some electrolytes to your intake and take a good
calcium/ magnesium supplement before bed with about 200-400 mg of magnesium
and 600-1000mg of calcium.