As one ages, collagen on the facial skin degrades—causing our skin to become weaker and thinner, and our facial muscles lose the ability to bounce back. The pull of gravity on the skin also becomes stronger. After decades of constant facial expressions (smiling and frowning) and being subjected to the effects of gravity, the eyebrows can begin to droop. In addition, the eyebrows tend to lose their arch, becoming more horizontal.
The end result is often a heavy-looking upper eyelid, with many people complaining that the droopy brows make them look older, tired and angry. Also, sagging eyebrows can block part of a person’s vision by making it hard to see past the eyelid skin.
To counteract sagging brows, people often lift and contract their forehead muscles. However, compensating for the sagging this way can cause deeper creases to appear in the forehead—compounding the problem.