Gabe Mirkin, M.D.
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. If you have this problem often,
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 most common cause of leg cramps in exercisers
is lack of salt.
The Food and Drug Administration has ruled that none of
the over-the-counter drugs used to treat night-time leg cramps
are recognized as safe or effective. The only drug that has been
shown to be effective in treating night-time leg cramps is quinine.
Doctors often prescribe 1 or 2 quinine pills at bedtime, but they
can cause birth defects and miscarriages, so they should never
be taken by a woman who may become pregnant. They can also
cause ringing in the ears, headache, nausea, disturbed vision,
chest pain and asthma.
March 25, 2006