Sleep latency is the amount of time it takes a person to fall asleep after going to bed and turning off the lights. It is an important measure of sleep health and is commonly used in both clinical sleep studies and consumer sleep tracking devices. In a healthy adult, sleep latency typically ranges from 10 to 20 minutes. Falling asleep too quickly — in less than 5 minutes — may indicate severe sleep deprivation or an underlying sleep disorder such as narcolepsy. On the other hand, taking more than 30 minutes to fall asleep on a regular basis may suggest insomnia or other sleep difficulties. Several factors can affect sleep latency. Stress, anxiety, and racing thoughts are among the most common causes of prolonged sleep latency. Caffeine consumption, exposure to bright or blue light in the evening, an uncomfortable sleep environment, irregular sleep schedules, and certain medications can also delay the onset of sleep. Conversely, physical exhaustion, sleep deprivation, and certain sleep disorders can shorten sleep latency to an unusually brief duration, which is not necessarily a sign of good sleep health. To improve sleep latency, it is helpful to establish a consistent bedtime routine that signals to the brain that it is time to wind down. Avoiding caffeine after midday, dimming lights in the evening, limiting screen time before bed, and keeping the bedroom cool, dark, and quiet can all support a healthy sleep latency. If persistent difficulty falling asleep is a concern, consulting a healthcare professional is recommended.