Medications that can cause restless leg syndrome as a side effect include antidepressants, antihistamines, and lithium.

A study this month found that more than 60 percent of patients over 65 experience moderate or major side effects the first time they are prescribed an antidepressant.

Compare that with antidepressant drugs, which cost Americans $10 billion each year and have many common side effects: sleep disturbances, nausea, tremors, changes in body weight.