Restless leg syndrome (RLS) is a form of insomnia characterized by an overwhelming urge to move the legs when they are at rest, especially during sleep. Recent research has found that people with restless leg syndrome are deficient in the mineral magnesium.
In one study from the Romanian Journal of Neurology and Psychiatry, researchers conducted biochemical and neurological tests in 10 cases of restless leg syndrome. The investigators reported important disorders of sleep organization. They found agitated sleep with frequent periods of nocturnal awakenings, and a decrease of the duration and percentage of the deeper rapid eye movement (REM) sleep - also found in other forms of insomnia caused by magnesium deficiency.
Clinical, EEG, electromyographic and polysomnographic studies in restless legs syndrome caused by magnesium deficiency. Rom J Neurol Psychiatry.1993 Jan-Mar; 31(1):55-61. PubMed PMID: 8363978.
Magnesium is important for muscles to be able to relax, while calcium helps them contract. Too little magnesium in relation to calcium (or low levels of both) can make muscles cramp more easily and may make some muscles, like the smooth muscles that wrap around big blood vessels, stay somewhat contracted.
Magnesium deficiency can make muscles go into spasms easily. When you're short on magnesium, the waste products of metabolism, such as lactic acid, are harder to flush out, so you may get tired, burning, sore muscles.