Yes, it can be a symptom of some underlying disease. Some of the diseases that may lead to fatigue include:
- Anemia
- Cancer
- Depression
- Diabetes
- Heart disease
- Obesity
- Stress
- Brain injury
- Lung disease
However, other factors, like stress, may also lead to fatigue.

The following symptoms are generally associated with fatigue:
- Headache and dizziness
- Muscle pain and weakness
- Loss of appetite
- Mood swings
- Blurred vision
- Hallucination
- Poor concentration
- Poor immunity

Wide range of factors may lead to fatigue and include:
- Medical conditions like anemia, hypothyroidism, fibromyalgia, heart disease or diabetes
- Emotional and workplace factors like stress, depression, anorexia, etc.
- Lifestyle factors like alcohol or drug abuse, and lack of physical exercise

Yes, depression leads to long-term sadness and hopelessness, which leads to tiredness and fatigue. Depression is one of the most common psychological factors causing fatigue.

When the fatigue is affecting your quality of life, causing distress and affecting your regular chores, you should consult a doctor to identify the underlying cause. If the fatigue is worsening without any change in your lifestyle, then it is cause for concern.