Causes of excessive tiredness

Short-lived fatigue may follow disrupted sleep, emotional strain, heavy activity, dehydration or an infection such as COVID-19. Ongoing low energy can occur with burnout, alcohol-related problems, thyroid or blood disorders, kidney disease, coeliac disease and other conditions. Chronic fatigue syndrome has a specific pattern that includes persistent exhaustion and worsening after activity, so it needs careful clinical assessment.

The details matter: snoring and morning headaches suggest a sleep-related issue; breathlessness or paleness can accompany anaemia; abdominal symptoms may point toward coeliac disease; fever, cough or loss of smell can occur with COVID-19. These clues guide rather than settle the diagnosis.

For several days, note sleep, activity, meals, mood, alcohol, medicines and accompanying symptoms. Keep a steady routine, eat regular nourishing meals and take gentle activity according to your energy. Arrange a primary-care review when tiredness lasts, interferes with work or self-care, or keeps returning. A clinician may examine you and consider blood or other tests based on your history.

Seek urgent help for chest pain, severe breathlessness, fainting, new confusion, one-sided weakness, black or bloody stools, or sudden extreme weakness. Contact a clinician promptly for persistent fever, unexplained weight change, marked thirst with frequent urination, or thoughts of self-harm.

Could my sleep, medicines, mood or diet explain this? Should I be checked for anaemia, infection, thyroid disease, kidney problems or coeliac disease? What activity level is sensible, and when should I return if energy does not improve?