To oversleep means to sleep longer than you intended or needed to. When you oversleep, you don't wake up when you planned to, and you end up sleeping past your alarm or missing an important time.

Maybe you stayed up too late reading and slept through your alarm the next morning, waking up twenty minutes after school started. Or perhaps you meant to wake up early on Saturday to go to soccer practice, but you didn't hear your alarm and woke up at noon instead. That's oversleeping: your body kept sleeping when you needed to be awake.

Oversleeping usually happens by accident. Your alarm might not go off, or you might be so tired that you sleep right through it. Sometimes people oversleep because they didn't get enough rest the night before, and their body really needs the extra sleep. Other times, oversleeping happens simply because you forgot to set an alarm.

The consequences of oversleeping can be minor, like missing breakfast, or more serious, like being late for an important event. Most people oversleep occasionally. If it happens once in a while, it's usually no big deal, but doing it regularly might mean you need to go to bed earlier or find a louder alarm clock.