Sleep-wake Cycle

The sleep-wake cycle is a 24 hours biological pattern of sleep and wakefulness in humans. It usually comprises seven to eight hours of sleep during the night and 16 hours of wakefulness in the daytime. It is controlled by the brain stem by communication with the hypothalamus. The body uses the circadian rhythm to control the sleep-wake cycle. The melatonin hormone secreted in the dark plays a major role in the regulation of the sleep-wake cycle. An irregular sleep-wake cycle causes insomnia and morning sleepiness. Increased exposure to blue light at night causes disturbance in the sleep-wake cycle.