I'd like to join Therising in welcoming you here to the Forum.
Lack of sleep is both a result of something, and also the cause of a lot of effects. Without good sleep feeling tired all the time is only natural, and if it goes on for to long then deprivation will case lapses in attention and clear thought.
It is however normally due to something. There are obvious causes like the bedroom being in a very noisy environment, or sharing with others who remain active, however if one discounts these then one needs to look further -as Therising has suggested.
It is not a normal thing, and the causes can be medical or psychological. I'm no doctor and am not qualified to even guess, then again neither are you. So getting a professional opinion is the only sensible way to go.
It may well be you have matters weighing on your mind, or are going though hassles in your life or have breathing difficulties when asleep. In any event setting everything out to your doctor is really the only way to go.
Can I assure you that you are not going mad no matter how you feel. Even the act of coming here and clearly setting out your problems shows a great degree of common sense and willingness to deal with problems.
May I ask if you can talk this over with your family and get them to arrange a GP's examination? If this is not an option then you can at your age arrange an appointment yourself, or seek advice from a person at school, maybe a teacher or councilor. Alternatively you can contact an organization such as the Kids Help Line (1800 55 1800) who are very understanding and used to such problems.
Please let us know how you get on