Like with Vit D, Mg, Iodine, Vit K, etc, etc the dose makes the poison. For a pasty white Scottish complexion like mine, 12 min / day full summer sun is optimal. Dark skin needs more. Red hair, albino, further north - need less.

Sunrise and sunset are the best times to get more subtle benefits of sunlight. The UV has been mostly filtered out, so no Vit D (or cancer). But the light does good things for mood and vision.