This document discusses insomnia, including its definition as difficulty falling or staying asleep. It notes that insomnia can be short-term or transient, caused by stressors like illness or travel, or long-term/chronic. Chronic insomnia can be caused by aging, as older people sleep less deeply and wake more easily, as well as by alcohol, caffeine consumption, and depression. The document provides tips for combating insomnia such as using blackout curtains, avoiding stimulation before bed, and eating a small snack.