One in eight Brits ‘exist in a state of constant exhaustion’, and a quarter feel tired most of the time, says a recent survey. But when does fatigue become a medical matter? And what can you do about it? One in eight Brits ‘exist in a state of constant exhaustion’, and a quarter feel tired most of the time, says a recent survey. But when does fatigue become a medical matter? And what can you do about it?