People come to the doctor saying, “I’m weak.” Or they may say “I get tired easily.” People who are healthy have vim and vigor. Ben Hecht once said: “They have bounce.” Elasticity in both mind and body is a sign of health. Those who lack energy and who are listless usually have something wrong. Such symptoms may be quite different from the loss of power in the muscles, which may be due to other causes. Just being unduly fatigued is also different from being faint or slightly dizzy.
Any physical or emotional disorder can be accompanied by lack of energy or listlessness. After an acute infection, following hemorrhage whether sudden or prolonged, or following long-continued subjection to cancer, this lack of energy may be a prominent symptom.
A severe emotional outbreak or upset leaves people weak, exhausted. Such outbreaks can also lead to depression or neurosis accompanied by anxiety.
Lassitude or languor may also be noted frequently as the result of insufficient action of the thyroid gland or from deficiency of secretion in the adrenal glands. However, excessive action of the glands can also lead to over stimulation and ultimate exhaustion.
Lassitude is often observed by the doctor in cases of chronic disease of the liver; in the old days people called this “debility.” Shakespeare says in As You Like It, “I did not woo the means of weakness and debility.”
Various drugs, by their effects or actions on the body can bring about lassitude, among these particularly bromides, alcohol, and the barbituric acid derivatives.