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alarm clock
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type of clock used to wake up a sleeping person at a certain time
An alarm clock is a device that makes a loud noise or sound at a preset time to wake someone up from sleep. It matters because it helps people wake up reliably at a specific time they need to be awake, such as for work or school.
AI-generated from the Wikipedia summary — may contain errors.
~13 min read
Encyclopedic overview
A traditional wind-up (key-wound), mechanical spring-powered alarm clock
An alarm clock or alarm is a clock that is designed to alert an individual or group of people at a specified time. The primary function of these clocks is to awaken people from their night's sleep or short naps; they can sometimes be used for other reminders as well. Most alarm clocks make sounds; some make light or vibration. Some have sensors to identify when a person is in a light stage of sleep, to avoid waking someone who is deeply asleep, which causes tiredness, even if the person has had adequate sleep. To turn off the sound or light, a button or handle on the clock is pressed; most clocks automatically turn off the alarm if left unattended long enough. A classic analog alarm clock has an extra hand or inset dial that is used to show the time at which the alarm will ring.
Excerpted from Wikipedia’s “alarm clock” article, available under the CC BY-SA 4.0 licence.