New York, Dec 4 (IANS): Vitamin D deficiency is not just harmful to physical health - it might also impact your mental health, says a new research.

The researchers found a link between seasonal depression (seasonal affective disorder or SAD) and a lack of sunlight.

"Rather than being one of many factors, vitamin D could have a regulative role in the development of SAD," said Alan Stewart of the University of Georgia' College of Education in the US.

The researchers conducted a review of more than 100 leading articles and found a relationship between vitamin D and seasonal depression.

"Seasonal affective disorder is a type of depression related to changes in season," Stewart added.

Vitamin D is involved in the synthesis of serotonin and dopamine within the brain, both chemicals linked to depression, according to the researchers.

Vitamin D levels of more than 50 nanomoles per litre are recommended by the US Institute of Medicine.

"What we know now is that there are strong indications that maintaining adequate levels of vitamin D is also important for good mental health," said Michael Kimlin from the Queensland University of Technology in Australia.

"A few minutes of sunlight exposure each day should be enough for most people to maintain an adequate vitamin D status," he added.

The findings appeared in the journal Medical Hypotheses.