Progeria (Hutchinson-Gilford Progeria Syndrome) is a rare genetic disorder characterized by accelerated aging in children. Those with Progeria experience rapid aging at approximately 8-10 times the normal rate, showing features of old age in childhood. It doesn't affect eating speed, reproduction rate, balding (they do lose hair early, but this is a symptom, not the defining characteristic), or sleep patterns. The accelerated aging leads to age-related complications in early life.