Fatigue that persists despite adequate sleep is one of the most common medical complaints — and one of the most important to investigate, as it can signal dozens of underlying conditions.
Fatigue is the overwhelming sense of tiredness, lack of energy, or exhaustion that is not relieved by rest. Almost everyone experiences fatigue occasionally, but when it becomes persistent — lasting two weeks or more — it warrants medical attention. In Korea, GPs at community health centres and private clinics are experienced in evaluating fatigue with targeted investigations.
The causes of persistent fatigue are numerous. Medical causes include anaemia (low iron or B12), hypothyroidism (underactive thyroid), type 2 diabetes, sleep apnoea, chronic kidney disease, heart failure, and depression. In Korea's working population, long working hours, high stress, and irregular sleep schedules are common contributors. Lifestyle factors — a sedentary routine, excessive screen time, poor diet, and insufficient hydration — also play a role.
Diagnosis typically begins with a blood panel including full blood count (FBC), thyroid function tests (TFTs), fasting glucose, ferritin (iron stores), renal function, and liver function. In many cases, a single treatable cause is found. Management varies: iron-deficiency anaemia responds well to iron supplementation; hypothyroidism is effectively managed with levothyroxine; depression responds to therapy and/or medication. Korea's community mental health welfare centres provide support integrated with primary care, making it easier than ever to address psychological contributors to fatigue.
Key Points
- Fatigue lasting 2+ weeks needs medical investigation
- Common causes: anaemia, thyroid disease, diabetes, sleep apnoea, depression
- Blood tests (FBC, TFTs, glucose, ferritin) often identify the cause
- Long working hours and irregular schedules are common contributors in Korea
- Sleep apnoea is common and highly treatable with CPAP therapy
- Community mental health centres integrate support for fatigue with psychological causes
Causes & Risk Factors
- Anaemia — iron, B12, or folate deficiency reduces oxygen delivery
- Hypothyroidism — slow metabolism causes constant tiredness
- Type 2 diabetes — blood sugar imbalance leads to energy swings
- Sleep apnoea — fragmented sleep despite adequate hours in bed
- Depression and anxiety — psychological fatigue often physical too
- Chronic kidney or liver disease — metabolic burden causes exhaustion
When to See a Doctor
- Fatigue lasting more than 2–3 weeks without obvious cause
- Fatigue with unexplained weight loss, fever, or night sweats
- Extreme fatigue making it impossible to carry out daily tasks
- Fatigue with chest pain, breathlessness, or palpitations
- Fatigue after a viral illness that isn't improving (possible post-viral syndrome)
For emergencies in Korea, call 119
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This content is published for educational purposes only. For accurate diagnosis and personalised treatment, consult a licensed KMA physician in Korea.
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Medical Disclaimer
This article is published by DoctorsInKorea.com for educational and informational purposes only. It does not replace a professional clinical evaluation by a licensed healthcare provider. For accurate medical diagnosis and personalised treatment paths, please book an appointment with a licensed KMA physician. For immediate life-threatening medical emergencies in Korea, please call 119.
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Last reviewed: March 1, 2025