wakeup

Wakeup refers to the act or process of waking from sleep, the transition from a state of sleep to wakefulness. It also denotes the state of being awake. In everyday use, wakeup can describe both the biological and environmental factors that terminate sleep and the routines or devices that bring a person or system to alertness. Neurologically, waking involves activation of arousal systems in the brain, modulation by circadian rhythms, and the gradual reduction of sleep inertia as waking progresses.

In humans and other animals, wakefulness is part of a daily cycle influenced by light exposure, hormones, and sleep pressure. Sleep inertia, a period of grogginess and reduced performance immediately after waking, is a common aspect of wakeup and can vary in duration. Proper wakeup processes are important for mood, cognitive function, and safety, particularly after nighttime sleep or during shift work.

In technology and computing, wakeup describes events or mechanisms that bring a device out of a low-power or sleep state. Examples include wake-on-LAN, which powers a computer remotely via a network message, wake timers scheduled by the operating system, and notifications that wake a smartphone or tablet to display information. Wakeup can also refer to a wake-up call, a service or reminder intended to alert someone or prompt action, as well as various sensors and protocols designed to trigger immediate activity upon certain stimuli.

See also: awakening, arousal, sleep inertia, alarm clock, wake-on-LAN, wake-up call.