Sleepless describes a state of being unable to sleep or a period without sleep. When you're sleepless, you lie awake at night, your mind racing or your body restless, unable to drift off no matter how tired you feel. A student might spend a sleepless night before a big presentation, tossing and turning with nervous energy. A parent with a sick child might have several sleepless nights in a row, staying awake to provide care.

The word can describe a person (sleepless and exhausted) or a time period (a sleepless night). Writers often use sleepless to convey worry or excitement: a detective might have sleepless nights puzzling over a difficult case, while a kid might be sleepless on Christmas Eve, too thrilled about the morning to relax.

Being sleepless occasionally happens to everyone, but consistent sleeplessness can affect concentration, mood, and health. People sometimes develop routines to help themselves sleep, like reading quietly, avoiding screens before bed, or keeping their room cool and dark. The experience of lying sleepless shows how much your body and mind depend on rest.