I very seldom have this problem. I don't know if it's because I use an electrolyte mixture (Hydralite) in my drinking water, which gives me potassium and magnesium. I take calcium supplements every day. Of course those multiple trips outside at night may help, too. Interstingly, I haven't had as many of those since I started using the Hydralite.

The inevitable question: Have you talked to your physician?