What Is Sleep Latency?

How Long It Takes to Fall Asleep

Sleep latency, also known as sleep onset latency (SOL), is the amount of time it takes to fall asleep once you go to bed. Ideally, sleep latency should be between 10 and 20 minutes. This lays the foundation for a solid, restorative night's sleep.

If you take longer than that to fall asleep, it can affect your sleep efficiency, or quality. And if you are behind on sleep, known as having a sleep debt, you may nod off as soon as your head hits the pillow. This reduced sleep latency is a sign you're not getting a healthy amount of sleep each night.

This article discusses the significance of sleep latency, how it is measured, and how you can improve your sleep latency if you are having trouble with your sleep.

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Significance of Sleep Latency

Ideal sleep latency is a good way to start your sleep. But sleep latency can also be too long or too short, which indicates some type of sleep disruption.

If it's too long, this can be stressful, because you might get frustrated that you can't sleep. Long sleep latency is a common sign of insomnia (trouble falling or staying asleep).

Short sleep latency means that you fall asleep almost immediately when you are ready for your daily long period of sleep (usually at night) or when you want to take a nap.

Sleep Efficiency and Sleep Latency

If you're able to fall asleep quickly, you're more likely to have efficient sleep.

Sleep specialists take the amount of time you spend asleep by the total time you spent in bed, then multiply it by 100. That gives them a percentage that's used to gauge your sleep efficiency.

  • 90% or higher = extremely good
  • 85% = normal
  • Below 85% = poor

Low sleep efficiency is usually a sign that something is preventing you from sleeping. It can be anxiety, chronic pain, a medical condition, or a variety of other factors. And the result is often feeling tired in the morning, which affects mood, concentration, and more.

Sleep Latency and the Sleep Cycle

An ideal sleep latency lays the foundation for a solid night's sleep, which occurs in stages throughout the night. The stages of sleep that occur throughout the night are cycles of rapid eye movement sleep (REM) and non-rapid eye movement sleep (NREM).

REM sleep is a deeper form of sleep than most NREM sleep, but both states are necessary for your overall health and are directly impacted by sleep latency.

The Impact of Sleep Debt on Sleep Latency

Sleep debt is the overall effect of not getting enough sleep. Sleep debt can accumulate over time, leading to mental and physical fatigue.

Sleep debt has a direct impact on sleep latency, since having a lot of sleep debt makes you extremely tired, meaning you'll likely fall asleep faster than someone who doesn't have any sleep debt.

Falling asleep almost immediately upon laying down is often a sign of sleep debt and, therefore, a sign that you should try to get more sleep on a nightly basis.

Measuring Sleep Latency

Sleep latency can be measured In several ways. One is with an overnight polysomnogram (sleep study) and another is with a multiple sleep latency test (MSLT).

An overnight sleep study can be done In a sleep laboratory or it can be done at home. It includes an electroencephalogram (EEG), which can detect stages of sleep. The study will also involve measuring your physical movements, body temperature, and oxygen level.

A polysomnogram can detect how quickly you enter into deep stages of sleep to determine whether your sleep latency is long, short, or ideal.

An MSLT is a daytime test that evaluates how quickly you fall asleep during the day when you are given an opportunity to nap after a night of sleep. This test is done in a healthcare setting. Falling asleep quickly during the day is a sign of short sleep latency.

Improving Your Sleep Latency

Your sleep latency is a helpful measure that provides insight into what factors could be involved In your sleep problems. Sleep latency is considered along with other aspects of sleep, most importantly, your symptoms. As a way to consider your symptoms on a measurable scale, you might be asked to respond to a sleep questionnaire, such as the Epworth Sleepiness Scale or the Pittsburgh Sleep Quality Index.

Your treatment depends on the cause, and the treatment is meant to address the whole sleep problem, not just sleep latency.

One of the common causes of long sleep latency is insomnia. Insomnia is often treated with lifestyle management, and sometimes medical management is needed if conservative measures are not effective or if insomnia is caused by a medical issue.

Sleep deprivation, which is associated with short sleep latency, has many causes and solutions. Overwork, medical conditions, sleep disorders, and insomnia are among the causes of sleep deprivation. Sometimes these are treated with lifestyle adjustments, and sometimes medical interventions are necessary.

Summary

Sleep latency is one of the measures of sleep quality. Normally, it should take you at least a few minutes to fall asleep when you go to bed. Falling asleep right away usually means that you are extremely tired, but tossing and turning for longer than 20 minutes before you fall asleep is considered a long sleep latency.

You might already have an idea of whether your sleep latency is normal and healthy, but sometimes an objective test can provide more information. If you are having trouble with your sleep, you and your healthcare provider can decide whether you need to change some of your daily habits to improve your sleep, or whether you need medical intervention.

A Word From Verywell

If you fall asleep immediately when your head hits the pillow, or if you are falling asleep even at times when you don't want to sleep—this often means that you have short sleep latency. It's a sign of fatigue, which can mean that you need more rest, or it could indicate a medical issue. And excessively long sleep latency is often a sign of things like anxiety or habits that are keeping you awake (like late-night screentime or evening caffeine intake). When it comes to something like sleep latency, you can often follow your gut feelings about how things are going. But if your sleep patterns are stressing you out, be sure to see a healthcare provider about it.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Jung DW, Hwang SH, Chung GS, Lee YJ, Jeong DU, Park KS. Estimation of sleep onset latency based on the blood pressure regulatory reflex mechanismIEEE J Biomed Health Inform. 2013;17(3):534-544. doi:10.1109/jbhi.2013.2257816

  2. Reed DL, Sacco WP. Measuring Sleep Efficiency: What Should the Denominator Be?J Clin Sleep Med. 2016;12(2):263–266. doi:10.5664/jcsm.5498

  3. Shrivastava D, Jung S, Saadat M, Sirohi R, Crewson K. How to interpret the results of a sleep study. J Community Hosp Intern Med Perspect. 2014;4(5):24983. Published 2014 Nov 25. doi:10.3402/jchimp.v4.24983

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.