Fatigue

Fatigue is tiredness or low energy that does not go away with normal rest. It is common after poor sleep, stress or an infection, and it can also be a sign of a health problem worth checking, like anemia or a thyroid problem.

When to get care

If you think it's an emergency, call 911 now. Don't wait to read this page.

When should I get care for fatigue?

Find the first group that matches. Each one is a MySymptom care level, from most to least urgent.

  1. Call 911 now

    • Sudden weakness on one side of the body, face drooping, slurred speech or confusion
    • Tiredness with chest pain or severe trouble breathing

  2. Get seen today

    • Fainting or nearly fainting
    • Shortness of breath at rest

  3. Call your doctor today

    • Very dark urine or yellow skin or eyes

  4. Book a visit

    • Tiredness lasting more than 2 to 3 weeks, or getting worse
    • Tiredness with weight change you can't explain
    • Feeling sleepy all day despite a full night in bed, or loud snoring

  5. Care for it at home

    • Tiredness after a busy stretch, poor sleep or a cold that improves with rest over a few days

If low mood comes with thoughts of harming yourself, call or text 988 now. It's free and private. 988 Suicide & Crisis Lifeline

What does fatigue feel like?

Fatigue can feel like physical heaviness, mental fog, low motivation, or all three. Some people describe it as 'wading through mud' or 'running on empty.' It often comes with poor concentration, irritability, and a need to rest after small efforts. Unlike normal tiredness, true fatigue isn't fully fixed by a good night's sleep.

What causes fatigue?

Fatigue is more than just feeling sleepy, it's a deep sense of low energy that doesn't fully lift even after a night of sleep. Almost everyone experiences short bouts of fatigue from a busy week, poor sleep, or a passing illness. Fatigue becomes worth investigating when it lingers for weeks, gets in the way of daily activities, or feels disproportionate to what you've been doing.

The causes of persistent fatigue are wide-ranging, from sleep quality issues and emotional health to nutritional gaps, anemia, thyroid changes, and chronic conditions. Because so many things can contribute, getting to the root often involves looking at sleep, mood, diet, hydration, exercise, stress, and any underlying medical conditions together rather than in isolation.

  • Poor sleep quality or quantity

    Going to bed late, waking often, snoring, or sleep apnea all reduce restorative sleep, leaving you tired during the day even after seven or eight hours in bed.

  • Stress, anxiety, and depression

    Mental health profoundly affects energy. Persistent low mood, anxiety, or burnout can cause fatigue that no amount of caffeine fixes.

  • Anemia and iron deficiency

    Low iron or low red blood cells reduce oxygen delivery to tissues, often causing fatigue, pale skin, breathlessness, and cold hands and feet.

  • Thyroid imbalance

    An underactive thyroid (hypothyroidism) commonly causes fatigue along with weight gain, dry skin, and cold intolerance.

  • Nutritional gaps

    Low vitamin D, B12, magnesium, or simply eating too little can leave you running on empty.

  • Chronic conditions

    Diabetes, autoimmune diseases, chronic infections, and heart or kidney issues are all common, sometimes silent, drivers of fatigue.

  • Medications

    Antihistamines, blood pressure medications, antidepressants, and many others list fatigue as a side effect.

How can I ease fatigue at home?

These steps are for mild symptoms with none of the warning signs above. Ask a pharmacist before taking any medicine.

  • Protect your sleep window

    Aim for a consistent bedtime and wake time, even on weekends. Keep the bedroom cool, dark, and screen-free for the last 30 to 60 minutes.

  • Move daily, even briefly

    Counterintuitively, regular light exercise, walking, gentle cycling, stretching, usually improves fatigue rather than worsening it.

  • Eat balanced, regular meals

    Combine protein, fiber, and healthy fats to keep blood sugar steady. Avoid skipping meals or relying on sugar and caffeine for quick lifts.

  • Hydrate steadily

    Even mild dehydration causes fatigue. Aim for steady water intake across the day rather than large amounts at once.

  • Manage stress proactively

    Short walks, slow breathing, journaling, or talking to someone you trust all help offload the mental load that drives fatigue.

  • Limit alcohol

    Alcohol fragments sleep even when it helps you fall asleep, and is a common hidden cause of next-day tiredness.

Common questions about fatigue

What's the difference between tiredness and fatigue?

Tiredness is the normal feeling that improves with sleep or rest. Fatigue is a deeper, more persistent low-energy state that doesn't fully resolve with rest, often accompanied by mental fog and reduced motivation.

Could it be my thyroid?

Possibly. Hypothyroidism is a classic cause of unexplained fatigue and is easily checked with a blood test. It's especially worth considering if you also have weight gain, cold intolerance, dry skin, or constipation.

Is afternoon energy crash normal?

A small dip after lunch is normal due to natural circadian rhythms. A severe crash, especially after a high-carb meal, may signal blood sugar swings, try smaller, more balanced meals and see if it improves.

Can iron deficiency cause fatigue without anemia?

Yes. Some people feel fatigued from low iron stores (low ferritin) even before their hemoglobin drops to anemic levels. A simple blood panel can check both.

Sources

Written by Arhaan Delawalla from the public guidance above. Not reviewed by a clinician. Updated .

MySymptom gives general health information. It is not medical advice and can't tell you for sure what is causing your symptoms. If you are worried, contact a clinician. In an emergency, call your local emergency number. How answers work