Over time, wrinkles and creases naturally form over the forehead. These are commonly referred to as frown lines or a low and sagging brow. These changes are a result of gravitational and involutional changes that result in eyebrows that rest lower than their normal position.
Facial expression and mood can be communicated by positional and relational changes of the forehead, eyebrow, and eyelids. Forehead wrinkles and sagging can suggest tiredness, sleepiness, or a worried effect when none is intended.