Magnesium is thought to combat fatigue because it helps release energy in the body. It also plays a role in the production of melatonin, which helps to regulate sleep; this production is disturbed when levels of magnesium are insufficient. As well as being helpful in treating fatigue and insomnia, magnesium plays a role in preventing and treating a host of other common ailments from the premenstrual syndrome (PMS) to heart problems.