Alarm clock

An alarm clock signals at a preset time, usually to wake someone or mark an event. It combines timekeeping with a trigger that activates a sound, light, vibration, or other alert.

Clock: A device that measures and displays time. An alarm clock adds a timed alert to a clock’s basic timekeeping function.
Mechanical clock: A clock powered by stored mechanical energy and regulated by a mechanism. Mechanical timekeeping made clock-driven alarm mechanisms possible.
Wake-up light: A lamp that gradually brightens before a set time to imitate sunrise. It uses light as a gentler wake-up signal than a sudden sound.
Biological clock: An internal timing system that coordinates recurring biological processes. It regulates sleep and waking without requiring an external alarm signal.
Quartz clock: A clock that keeps time by using the regular oscillations of a quartz crystal. Many electronic alarm clocks use quartz oscillations to keep time accurately.
Levi Hutchins: An American clockmaker credited with creating an early personal alarm clock in 1787. His clock reportedly sounded at a fixed time rather than a user-selected one.
Vibrating alarm clock: An alarm clock that wakes users with a vibrating pad or device. It can alert people who are deaf or hard of hearing without relying on sound.
Circadian rhythm: A roughly 24-hour cycle in biological activity shaped by internal timing and environmental cues. A regular rhythm may support waking near a chosen time without a clock alarm.
Alarm circuit: An electronic circuit that activates an alert when a set condition is met. It compares the current time with the alarm setting and switches on the alert.
Antoine Redier: A French inventor who patented an adjustable alarm clock in 1847. His design allowed the alarm time to be set rather than fixed.

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NightstandRelated: Its bedside placement makes the time and wake-up alarm accessible overnight.