What brings on "charlie horses" in legs at night?

A rude awakening...: The most common reason for calf cramps is dehydration, electrolyte abnormalities, certain medications, and recent excessive muscular activity. Some medications can deplete your potassium or calcium, magnesium levels. Adequate hydration would be the first thing to try. Consider a nightly gin and tonic without the gin… Tonic water contains quinine in small amounts and sometimes works wonders!