Magnesium deficiency - and life without it ...
 

Magnesium is a must. The diets of all Americans are likely to be deficient........Even a mild deficiency causes sensitiveness to noise, nervousness, irritability, mental depression, confusion, twitching, trembling, apprehension, insomnia, muscle weakness and cramps in the toes, feet, legs, or fingers.

Adelle Davis, writing in Let's Have Healthy Children
http://www.ctds.info/5_13_magnesium.html