I think it could be one, or the other, or both - depending on the person, Abainaa.
I believe the cycles that affect the earth (seasons, tides, moons) affect our bodies as well (menstruation is an example). So it could be the natural cycle of our follicles that causes the shedding, or our bodies response to external changes happening in theatmosphere - but it happens to me every year at this time of year, like clockwork. It just started this week....
I get a little scalp flaking too...same deal I think. My scalp NEVER flakes, but when fall rolls around my body starts sloughing....skin, hair, weight....
It all gets some pruning.