I know it doesn't seem possible you could get blue in the summer. With so much sunlight and all. Years ago, I lived for the sun (my skin is paying for it now). My friends jokingly nicknamed me the "sun goddess". Intuitively, I craved the sun, like I couldn't get enough. Then after receiving a spectra-cell analysis test, I found out my blood was not holding vitamin D.
With all that sun! How could it be. My doctor's conclusion was that my body was not able to synthesize the Vitamin D from the sun. So now I do take it as a supplement. What a difference! My immune system works better and my depressive symptoms have been much more manageable. Of course, I always encourage people to get their nutrients from food, but sometimes supplementation is beneficial.