Nocturnal leg cramps are sudden, involuntary contractions of the calf muscles that occur during the night or while at rest. The cramps can affect persons in any age group, but they tend to occur in middle-aged and older populations. Sometimes muscles in the soles of the feet also cramp.
Sometimes the cramps are caused by overexertion of the muscles, structural disorders (flat feet), standing on concrete, prolonged sitting, inappropriate leg positions while sedentary, or dehydration. Doctors do know that those who are more muscular seem to have more leg cramps. Less common causes include diabetes, Parkinson's disease, hypoglycemia, anemia, thyroid and endocrine disorders and use of some medications.
Low levels of certain minerals known as electrolytes – magnesium, potassium, calcium and sodium – have long been linked to leg cramps. (Marathon runners sweating out the miles are particularly prone to this variety.) Certain drugs, such as diuretics have also been cited as a cause of leg cramps. Dialysis patients often complain of leg cramps, and pregnancy is also a factor.
Persistent or severe leg cramps often are treated with medication. Such medications include diphenhydramine hydrochloride (Benadryl), simple muscle relaxants such as meprobamate (Equanil, Miltown) and verapamil hydrochloride (Calan, Isoptin, Verelan). Quinine, while effective, has too many side-effects and has been banned in the US for this use.
To prevent cramping consider the regular use of supplements, especially calcium, magnesium, potassium and sodium (only if your sodium intake is low or if you sweat a lot). Stretching your calves regularly during the day and at night will help. 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 going to bed. Keeping blankets loose at the foot of the bed will help prevent unnatural positioning of your feet and toes which can cause night time cramping.
An IND (Investigational New Drug Application) has been filed with the FDA for GHB's proposed action on reducing nocturnal myoclonus (painful leg cramps at night).
Exercise, such as riding an exercise bicycle for a few minutes before bedtime, can help prevent cramps from developing during the night, especially if a person does not get a lot of exercise during the day.
Because of its nerve and muscle support, magnesium may also be helpful for muscle cramps. Some people taking magnesium may get relief from leg cramps right away, but a long-standing deficiency can take weeks to overcome with supplements.
Nocturnal leg cramping often responds to 400-800 IU of vitamin E per day. In one of the largest studies, 103 of 125 people who had been experiencing leg and foot cramps at night reported relief after taking vitamin E. A daily dose of 300 IU was effective for half of the participants, while the others required 400 IU or more for relief [Ayres, Mihan. South Med J. 67(11): pp.1308-12,1974]