Vitamin D deficiency may also lead to seasonal mental depression or seasonal affective disorder in humans, a review study suggests. Apart from other causative factors, vitamin D influences the development of seasonal depression in humans.
Depending on the geographical location, seasonal affective disorder occurs during fall and continues through the winter seasons, every year.
The circulatory levels of vitamin D varies from one person to another depending skin color. Low circulatory levels of vitamin D were observed in dark-skinned patients who were also diagnosed with depressive disorders. Individuals with greater skin pigmentation may suffer vitamin D deficiency in addition with increased risk of developing depressive disorders. The study concluded that depressive disorder patients had low blood levels of vitamin D.