Vitamin D and its affect on the brain

Summary:  Vitamin D is necessary for a multitude of functions, from maintaining strong bones to benefiting the immune and cardiovascular system.  Now, in a new experiment from Thomas Burne it was found that a lack of vitamin D may result in a decrease in perineuronal nets in the hippocampus.  Lack in vitamin D also causes weaker and less neural connections.  These ultimately causes a decrease in cognitive function.  This could be a factor in symptoms of schizophrenia such as memory loss and cognitive disorders.  This causes a decrease in the ability to learn and memorize new things.

Connection to health class:This connects to health class because we are told that going outside is always important.  We are also told about maintain a healthy lifestyle which now includes getting vitamin D and going outside. Lastly, during the brain unit we learned about the brain, which this discusses.

Question:  How much vitamin D is an adequate amount, and how many hours of sunlight is required for that to be achieved?