The barrier meets colder, drier air

Cold air holds far less water than warm air, and indoor heating strips out what remains. That creates a steeper gradient pulling moisture up and out of the skin, a process called transepidermal water loss.

The outermost layer, the stratum corneum, relies on a matrix of lipids and water to stay flexible and sealed. Through winter that matrix is under constant draw, and a barrier that coped easily in humid warmth begins to lose ground.

Drier skin is two problems at once

In the cold, water leaves faster, and the skin produces less of the oil that would normally slow that loss.

Sebum output drops, and the lipids and ceramides that hold the barrier together are used up faster than they are replaced.

A barrier short on lipids is a barrier that leaks. This is also why dehydrated skin is not the same as dry skin. Dehydrated skin cannot hold the water it already has, which is why it can feel tight and look flat even when it is not lacking oil.

The response is not simply a heavier cream. The Rich Repair Moisturiser, a non-occlusive moisturiser can be blended with your serums in the evening, it suits dry, sensitive or barrier-compromised skin without the heavy film that traps rather than repairs.

Why it looks duller and reacts more

Cold triggers vasoconstriction. Blood vessels narrow to conserve heat, so less blood reaches the surface. Circulation is part of what makes skin look awake and part of how quickly it repairs.

Move repeatedly between cold outdoors and heated indoors and those vessels dilate and constrict in turn, which is why redness and flushing tend to worsen in winter, particularly for reactive and rosacea-prone skin.

A weakened barrier also lowers tolerance. Actives that felt comfortable in summer can start to sting, because the barrier that used to buffer them is thinner.

A gentler cleanse can help reactive skin which is why the Calming Cream Aloe Cleanser is the one to reach for in the colder months, morning and night.