Tiredness or fatigue is one of the most common ailments that people go to their GP with.
One study found that it's responsible for around six in every 100 GP visits.
It's so common, in fact, that doctors use the acronym TATT, which means 'tired all the time'.
Dr Doireann O'Leary, health blogger and Cork GP, joined us for our weekly health slot to explain some of the medical causes of fatigue.