What causes extreme lack of energy, daytime tiredness and difficulty focusing?

Multiple causes. There can be multiple causes, both medical and psychiatric, for this cluster of symptoms. I recommend that you begin evaluation with your primary care provider, where you are likely to start by ruling out common medical causes for theses symptoms such as anemia or hypothyroidism.

Related Questions

Extreme lack of energy, daytime tiredness and difficulty focusing due to stress?

Not sure of question. If these are new symptoms, i'd strongly recommend that you have a check-up, first with your primary care doctor. There are lots of physical conditions that can cause these symptoms, as well as psychiatric ones such as depression and anxiety. You deserve a better life, and the first step well may be finding out what is going on. If it is "just" stress, then you may need help dealing with that. Read more...