When you are tired all the time the vitamin that a person is usually lacking when they are tired all the time is Vitamin D.
You could have a Vitamin D deficiency and should see your doctor about it.
You can take Vitamin D supplements to increase your vitamin D intake which can help you stop feeling tired all the time.
You might have other deficiencies as well that are causing you to feel tired all the time such as vitamin B-12, iron, magnesium, or potassium deficiencies.
Another thing that can make a person feel fatigued and tired all the time is Anemia which is a low iron count which can lead to kidney failure if not treated in time.
So always get checked out by a doctor to determine what the actual cause is for your fatigue or tiredness all the time.