Sleep onset

Sleep onset is the transition from wakefulness to sleep, and the time it takes is called sleep onset latency.

For most adults the transition takes roughly ten to twenty minutes. Falling asleep almost instantly can signal sleep deprivation, while regularly taking more than thirty minutes is a defining feature of sleep-onset insomnia. Factors that delay onset include an active mind, anxiety, caffeine, bright light and screens in the evening, an irregular schedule and a bedroom that is too warm or noisy. Circadian rhythm disorders can shift the natural time of onset later or earlier.

Sleep onset latency is estimated from a sleep diary or measured with actigraphy or polysomnography, where it is defined by the first appearance of sleep on brain-wave recordings. It is one of the most common outcome measures in sleep research. Cannabinoids have been studied for sleep onset in small trials, with results that vary by compound and study design.