For many of us, sleep is the sweet balm that soothes and restores us after a long day of work and play. But for those for whom sleep is elusive or otherwise troubled, the issue is far more fraught. Most people, at some point in their lives, experience difficulty falling asleep. Other parasomnias—such as sleep apnea, night terrors, narcolepsy, and sleep paralysis—are surprisingly common. The good news is that treatment of sleep disorders is progressing rapidly, with new advances appearing every month.