Constant tiredness and sleepiness: possible causes and which doctor to see

Tiredness that doesn't go away after rest can be linked to sleep, stress, low iron, the thyroid, a recent infection or medicines. There are many causes, and one symptom alone can't tell you which it is.

Start with your GP: they will ask questions, examine you and decide which tests you need and who to see next. Before the appointment, write down when it started, how much you sleep and what else has changed. If the tiredness comes with weight loss, fever or breathlessness, don't put the visit off.