What causes persistent fatigue despite sleep, and when are tests needed?
Persistent fatigue has many possible causes, including poor sleep quality, medicines, stress, anaemia and other conditions. Sleep duration alone cannot exclude a health problem. Fatigue does not by itself establish a vitamin deficiency or ME/CFS.
Details
Describe the pattern
Explain duration, impact on work, snoring or witnessed breathing pauses, mood, weight changes, bleeding and medicines. History and examination guide testing instead of universal laboratory panels or supplements.
Exercise advice must fit the condition
Report marked worsening after minor exertion, especially when it lasts hours or days. If ME/CFS is suspected, activity should respect energy limits; programmes imposing fixed increases in exercise are not recommended for this condition.
Follow-up and warning signs
Seek review when fatigue lasts weeks or disrupts daily life, even after initially normal tests. Chest pain, severe breathlessness, fainting or significant bleeding needs urgent care and should not be dismissed as ordinary tiredness.
Related reading: Why do I feel colder than other people?.