Vitamin D is proven to improve mood. But you have to take D3. That is the form that your body turns Vitamin D into. So your body gets usable Vitamin D. Also you need to take other supplements to go with Vitamin D. Your body need Calcium and Magnesium to absorb the Vitamin D.
Take the Magnesium at night. Your body absorbs in better in your sleep. Take about two hundred Mg of Mag and Cal for every 1,000 Mg's of Vitamin D 3. The suggested daily amount will not improve your state. Try it out and see where your state improves. 3-5 thousand units of Vitamin D 3 are usually needed to improve mood and cell function.
I live with clinical depression. This seriously improved my state like night and day. But it works for everyone. When your body's cells get enough Vitamin D3 it improve cell health and growth.
You know that tingely feeling you get in the summer time. Vitamin D no joke it makes your state a natural high.