Guess my surprise on hearing this!! When all the while I used to marvel at how someone can be deficient in the most available vitamin, I found out that I am one of the lot. Like one of the reader mentioned in her comment, my Vitamin levels are almost at 3-4 out of the scale of 30. I came to know of this when I got my complete blood test done. But, I have yet to consult a doctor on this!!
Vitamin D deficiency has become so prevalent now. Even my FIL suffers with the same and apparently someone told him that his knee pains are due to the same reason. In fact, my boss was diagnosed with extreme low levels of Vitamin D and was given shots for it. And, since then, he has been feeling much better with high levels of energy and lesser other health issues.
Now, if you feel tired all the time or drowsy and suddenly start feeling a lot of joint pains and aches, you might want to go to a doc and get yourself tested for Vitamin D. Of course, do not rush to doc right away but analyze how your body is feeling. If you know your body well, you will know when something is wrong with it.
Have you been tested for Vitamin D?