Nighttime leg cramps. Is there no rest?

In a sound sleep, with thoughts of sugar plums or a sandy beach dancing about in your head, a pain in the leg or the foot

makes its presence known with high drama. The discomfort is sharp, knifelike and will not go away. The only hope for relief

is to address the forcefully extended foot or the toes curled inward like a dying spider. Muscular cramping is a common

malady. Almost two-thirds of us will report its presence at some point and one in five are so bothered that they bother

someone else about it. Cramping is very different from another common malady, Restless Legs Syndrome. RLS is marked by

discomfort or feeling ill at ease without standing, walking or otherwise moving the legs. Muscular contraction is not its source

of discomfort. The phenomenon of nocturnal leg cramping is poorly understood and its cause is not known with certainty.

During athletic endeavors, cramping occurs with muscle fatigue but this is not the same as the nighttime visitor. Electrical

observation of muscle cramping suggests that the origin is most often in the nerves that command them. Although deficiency

in calcium, magnesium or potassium may be marked by muscular symptoms or spasm, they are not implicated in the

common nocturnal leg cramp. Medicines are often blamed but to date, the only strong evidence points to estrogens,

intravenous iron and cancer treatments.

The list of suggested remedies for nocturnal cramping is long and includes, muscle relaxers (carisoprodol), the blood

pressure medicines called calcium channel blockers (verapamil, diltiazem) and Quinine. Quinine is the magical component of

the Peruvian bark and the source of bitterness in tonic water. It is the original antibiotic produced on a large scale and was

used to treat malaria. In addition, happy accident found it to be a manipulator of biological electricity as well as boon to the

muscular cramp. Of the medicines offered for cramping, Quinine is the only one proven effective but its potential for

dangerous, even lethal side effects is such that it is best avoided. (1) Magnesium is one of the aforementioned parts of salts

whose deficiency may cause cramping. It is necessary for every cell to function and depleted from the body by many

medicines and illnesses. However, the fact that deficiency causes a problem does not mean that routinely taking extra will

prevent the same problem is something else is at fault. Nonetheless, magnesium supplementation, which is not completely

risk free, is often turned to as a cramping remedy. Thus was born the study.(2)


In a group of people complaining of nighttime leg cramps, will Magnesium supplementation affect their complaints?


In Israel, adults who reported at least four episodes of cramping in the previous two weeks were given either a magnesium

oxide pill or a similar-looking placebo to be taken at bedtime for a period of 4 weeks. They recorded their symptoms.

Ninety-four people participated. They were older, about 65 and six of ten were women. At the beginning, almost everyone

had daily symptoms. At the end, almost everyone reported three fewer episodes each week and it made no difference if

they were given Magnesium or placebo. Therefore, magnesium supplementation cannot be counted on to improve symptoms

of nocturnal leg cramps. The authors pointed out that everyone improved suggesting that nocturnal cramping treatment may

be subject to significant placebo effect.

Impact and analysis

If you have bothersome leg discomfort that impairs your rest, the first step is to talk to your doctor. He or she may recognize

Restless Legs Syndrome or identify a medicine or metabolic disturbance as the source of the problem. RLS is very

responsive to medical treatment. If muscular cramping is the cause, supplementing salt intake with magnesium or potassium,

should only follow identification of a deficiency. In absence of such, magnesium clearly has no value and potassium may

be dangerous. Curcumin, a component of the yellow spice, Turmeric has an abundance of anecdotal reports with no

underlying rationale or trial evidence. Many physicians recommend, also with little evidence, specific muscle relaxers and

calcium channel blockers. The only medication with evidence of usefulness, Quinine is also potentially dangerous and not

recommended. Therefore, there is little to offer the cramp afflicted save reassurance, a bit of benign neglect and perhaps a

recommendation to keep the legs warm at night.

Keywords: Nocturnal cramp, Magnesium

1. El-Tawil S, Al Musa T, Valli H, Lunn MP, Brassington R, El-Tawil T, et al. Quinine for muscle cramps. The Cochrane database of systematic reviews. 2015(4):Cd005044.

2. Roguin Maor N, Alperin M, Shturman E, et al. Effect of magnesium oxide supplementation on nocturnal leg cramps: A randomized clinical trial. JAMA Internal Medicine. 2017;177(5):617-23.