Brow Drooping

The eyebrow is held up by the forehead's skin, muscle and the deep fat at the temple. As collagen declines and that deep volume shrinks, the support holding the brow weakens and it drifts downward. Even a few millimetres press extra skin onto the upper eyelid, which makes the eyes look heavier and more tired.

Collagen and elastin are the skin's support fibres, made deep in the dermis by cells called fibroblasts. With age these cells slow down, so less new collagen forms while the collagen already there fragments and weakens. Elastin, which lets skin spring back, is barely renewed after youth, so the skin of the forehead firms up less and gradually loosens.

The temple is cushioned by deep fat and bone. As both lose volume with age, the outer brow loses its prop and sinks, much like a tent losing tension at one corner. This is why the tail of the brow, on the outer side, usually drops first.

The forehead and upper brow face the sky and absorb a great deal of direct sunlight. UV steadily weakens the collagen and elastin that hold the brow in place, and repeated squinting against bright light adds expression lines. Together they let the brow lose height and settle lower over the years.

Everyday habits weigh on the brow too. Smoking, alcohol, pollution and short sleep generate oxidative stress that breaks down the support fibres in the forehead, and a sugar-rich diet stiffens them through glycation. As this scaffolding weakens, the forehead skin gives way and the brow drifts downward more readily.