Most of the time, if i come in brief contact with direct sunlight i get sick. why is that? do i have some deficieny or health issue?

Heat intolerance: this is likely to be a kind of heat intolerance, the common causes for that is strenuous exertion in hot weather, and that can be made worse with dehydration (lack of water intake), low physical fitness, obesity below link to more information https://www.uptodate.com/contents/heat-stroke-the-basics?source=search_result&search=heat+exhaustion+adult+patient+info&selectedTitle=1%7E13