Low energy is caused by a variety of factors including a normal response to insufficient sleep, heart and lung problems, psychosocial or neurological conditions, and a number of diseases, disorders and conditions. A life-threatening lack of energy can be caused by a drug overdose, electrolyte imbalances, arrhythmia or severe infection, states Healthgrades.
When a person experiences low energy levels because of factors such as overexertion, stress and lack of sleep, energy levels rise as soon as the person practices stress management, eats properly and gets enough rest and sleep. Persistent low energy levels may be a sign of an underlying disease or condition, notes Healthgrades.
Lung and heart problems that can cause a person to have low energy levels include coronary artery disease, irregular heartbeat and pneumonia, while drug and alcohol abuse, anxiety disorders and grief are a few psychosocial and neurological conditions that can cause low energy levels. Other diseases and disorders that can cause a person to have a lack of energy include anemia, diabetes and thyroid conditions, explains Healthgrades.
Lack of energy on its own is not usually a medical emergency. However, if it develops suddenly or if it is accompanied by other serious symptoms, the person should seek medical attention urgently to avoid significant complications, according to Healthgrades.