Psychiatrist Dr Sarthak Dave explains that insomnia is difficulty falling asleep, maintaining sleep, or waking too early, often leading to fatigue, poor focus, mood swings, and low motivation. It can be transient (lasting days to weeks), short-term (less than 3 months), or chronic (3 months or more), and is classified as sleep-onset, sleep-maintenance, or early-morning awakening insomnia.