Lethargy

Not to be confused with Fatigue.

For the 1990s band, see Lethargy (band).

"Low energy" redirects here. For low-energy electronics, see Low-power electronics.

Antoine Marie, overcome with lethargy, buried, seemingly dead in 1696

Lethargy is a state of physical or mental weariness, fatigue, sluggishness, or lack of energy. It can be accompanied by depression, decreased motivation, or apathy, but can also present with having a desire, but not the energy to initiate or perform tasks.^[1] Lethargy can be a normal response to inadequate sleep, overexertion, overworking, stress, lack of exercise, improper nutrition, drug abuse, boredom, or a symptom of an underlying illness or disorder. It may also be a side effect of medication or caused by an interaction between medications and alcohol. It may also be an altered level of consciousness.^[2]

When part of a normal response, lethargy often resolves with rest, adequate sleep, decreased stress, physical exercise, and good nutrition.^[3] Its symptoms, however, can last days or even months,^[4] so it can be a sign of a recent underlying illness or infection if it does not resolve normally.

Etymology

The word lethargy originates from the Ancient Greek noun λήθαργος (lēthargía), formed from the adjective λήθαργος (lēthargos), which means "forgetful". It is root to the River Lethe, one of the five rivers in the Greek underworld whose waters caused those who drank from it to experience complete oblivion and forgetfulness.^[5]

See also

• Clinical depression
• Disorders of diminished motivation
• Encephalitis lethargica
• Sleep apnea
• Sleep deprivation
• Somnolence
• Altered level of consciousness

References

1. "Lethargy (Concept Id: C0023380) - MedGen - NCBI". www.ncbi.nlm.nih.gov. Retrieved 2026-05-18.
2. Tindall, Suzie C. (1990), "Level of Consciousness", in Walker, H. Kenneth; Hall, W. Dallas; Hurst, J. Willis (eds.), Clinical Methods: The History, Physical, and Laboratory Examinations (3rd ed.), Boston: Butterworths, ISBN 978-0-409-90077-4, PMID 21250221, retrieved 2022-03-26
3. Hall J. E., Guyton A. C. (2006): Textbook of medical physiology, 11th edition. Elsevier Saunders, St. Louis, Mo, ISBN 0-7216-0240-1.
4. "Chronic fatigue syndrome - Symptoms and causes". Mayo Clinic. Retrieved 2022-03-26.
5. "It's Greek to Me: LETHARGY | Bible & Archaeology - Office of Innovation | The University of Iowa". bam.sites.uiowa.edu. Retrieved 2026-10-19.

External links

• The dictionary definition of lethargy at Wiktionary