Why Am I Always Tired? 7 Common Causes of Chronic Fatigue

Chronic fatigue can impact every aspect of your life — from work performance to relationships. While occasional tiredness is normal, persistent exhaustion that doesn't improve with rest may signal an underlying health issue. Here are 7 of the most common medical causes: 1. Iron-Deficiency Anemia When your body lacks sufficient iron, it cannot produce enough hemoglobin to carry oxygen to tissues. This leads to persistent fatigue, weakness, and pallor. Women with heavy periods and vegetarians are at higher risk. A simple complete blood count (CBC) can diagnose this. 2. Hypothyroidism An underactive thyroid gland slows your metabolism, causing fatigue, weight gain, and cold sensitivity. Thyroid disorders affect roughly 5% of the population and are diagnosed through TSH blood tests. 3. Sleep Apnea This condition causes brief breathing interruptions during sleep, preventing restful rest even after 8+ hours in bed. Loud snoring, morning headaches, and daytime sleepiness are hallmark signs. 4. Vitamin D Deficiency Low vitamin D levels are linked to fatigue, muscle weakness, and mood changes. People who spend limited time outdoors or live in northern climates are particularly susceptible. 5. Depression Mental health conditions often manifest physically. Depression can cause profound fatigue alongside persistent sadness, loss of interest in activities, and difficulty concentrating. 6. Diabetes (Type 2) When cells cannot effectively use glucose for energy, fatigue becomes a primary symptom. Frequent urination, excessive thirst, and unexplained weight changes often accompany diabetic fatigue. 7. Chronic Stress and Burnout Prolonged stress elevates cortisol levels, which disrupts sleep quality and drains energy reserves. Burnout is characterized by emotional exhaustion, detachment, and reduced performance. When to See a Doctor Seek medical evaluation if your fatigue persists for more than two weeks despite adequate sleep, is accompanied by unexplained weight loss, or is severe enough to interfere with daily activities.