What could be causing me to feel so tired all the time?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Constant fatigue has several possible causes, including anemia, depression, thyroid disorders (such as hypothyroidism), sleep disorders like sleep apnea, chronic fatigue syndrome, diabetes, vitamin deficiencies, or ongoing stress. Because tiredness can stem from many overlapping conditions, identifying the root cause requires proper medical evaluation.

Not sure where to start? Before booking an appointment, take a free, instant, online symptom check to explore possible causes based on your specific symptoms. It takes just a few minutes, requires no sign-up, and can help you understand what may be driving your fatigue—so you can walk into your next doctor's visit informed, prepared, and one step closer to feeling like yourself again.

Reviewed for medical accuracy: 07/14/2026

Important Next Steps

Discover causes of your constant fatigue See if tiredness needs medical attention Find out what’s causing persistent exhaustion Explore OTC options for fatigue relief Find a doctor for ongoing fatigue Understand evidence-based home remedies for tiredness Check if fatigue could signal something serious

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Explanation

A person can feel tired (also known as fatigue) for various reasons. For example, fatigue can be a symptom of anemia, depression, a thyroid problem, or a sleep disorder, among other possible causes.

Anemia is when the number of red blood cells in the body is lower than normal; there are multiple reasons why someone may have anemia and a healthcare provider can investigate what may be causing anemia (and/or fatigue). When someone is experiencing depression, they can have symptoms including mood changes as well as feeling sleepy and/or lacking energy. When the thyroid does not make enough thryoid hormone, a person can feel tired all the time. Sleep disorders include sleep apnea, restless leg syndrome, and other conditions.

If you are wondering why you often feel tired, you can use Ubie's free AI symptom checker to help identify possible causes, then contact a healthcare provider to receive a personalized medical evaluation and advice.

(References)

Baldwin DS, & Papakostas GI. (2006). Symptoms of fatigue and sleepiness in major depressive .... The Journal of clinical psychiatry, 16848671.
Maestri M, Romigi A, Schirru A, Fabbrini M, Gori S, Bonuccelli U, & Bonanni E. (2020). Excessive daytime sleepiness and fatigue in neurological .... Sleep & breathing = Schlaf & Atmung, 31444679.
Ridsdale L, Evans A, Jerrett W, Mandalia S, Osler K, & Vora H. (1994). Patients who consult with tiredness. The British journal of general practice : the journal of the Royal College of General Practitioners, 8790655.

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