Have you been awakened in the middle of the night by a sudden painful cramp in your leg? So have lots of other people.

Cramping during sleep is usually due to an exaggeration of a normal muscle reflex. When you turn during sleep, you contract your calf muscles and stretch their tendons. This stimulates nerve stretch receptors in the tendon and sends a message back to the spinal cord, telling the calf muscles to contract. Sometimes, the muscles remain contracted and hurt. Painful muscle cramps at night can also be caused by nerve damage such as that caused by pinching a nerve, muscle damage, a partially-obstructed flow of blood to the legs, or abnormal mineral or hormone levels, so if you have this problem, check with your doctor. If you do not have a serious cause, you can often prevent night cramps by exhausting the stretch reflex before you go to bed by stretching your calf muscles with wall pushups, and applying a heating pad for 10 minutes before you go to sleep.

The only drug that has been shown to be effective in treating night-time leg cramps is quinine, but the Food and Drug Administration stopped over-the-counter marketing of this remedy because of concerns about irregular heart beats and other side effects. Doctors may still prescribe quinine pills for relief of leg cramps, but they can cause birth defects and miscarriages, so they should never be taken by a pregnant woman. Quinine can also cause ringing in the ears, headache, nausea, disturbed vision, chest pain, asthma and other problems.

By Gabe Mirkin, M.D., for CBS News Radio
Checked 3/1/19

1) KM Leclerc, FJ Landry. Benign nocturnal leg cramps: Current controversies over use of quinine. Postgraduate Medicine 99: 2 (FEB 1996):177.

2) FDA Consumer November, 1994.

3) Quinine does not help to prevent or treat night-time leg cramps. Journal of the American Geriatrics Society June, 1993.

4) M Mansonhing, G Wells. Meta-analysis of efficacy of quinine for treatment of nocturnal leg cramps in elderly people. British Medical Journal 310: 6971 (JAN 7 1995):13-17-The results of six double-blind studies show that quinine can prevent nocturnal leg cramps in general ambulatory populations.