Deficiency/Insufficiency is also a common reason for seasonal depression. Less sunlight = less vitamin D. 40-60 ng/mL is a commonly preferred range and is usua

Deficiency/Insufficiency is also a common reason for seasonal depression. Less sunlight = less vitamin D. 40-60 ng/mL is a commonly preferred range and is usually achieved with 50-100 IU/kg vitamin D3 (ie, 3500-7000 IU at 70 kg). Dose calculator (assume 0 ng/mL if current level unknown): http://vitamindservice.com/node/87 http://vitamindservice.com/node/87.