I am tired throughout the day and I can't concentrate as well as I used too, my doctor said I have a low blood pressure and I sleep little. What is it?

Low BP and insomnia. Keep discussing your symptoms with your dr. As adequate sleep is paramount to functioning well throughout the day. Getting your sleep disorder treated is important and getting an evaluation as to why you have low BP is also important, as that can be treated too, hopefully making you more alert. Good luck.