Sleep Disorders Sleep Latency and Its Impact on Your Sleep By Brandon Peters, MD facebook twitter Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist. Learn about our editorial process Brandon Peters, MD Medically reviewed by Medically reviewed by Sanja Jelic, MD on August 10, 2020 Sanja Jelic, MD, is board-certified in sleep medicine, critical care medicine, pulmonary disease, and internal medicine. Learn about our Medical Review Board Sanja Jelic, MD Updated on December 07, 2020 Print Sleep latency, also known as sleep onset latency or SOL, is the amount of time it takes to fall asleep after the lights have been turned off. Ideally, it should take a brief amount of time to fall asleep after the lights have been turned off, but not too long. The time it takes one to fall asleep after the lights are turned off relates directly to sleep efficiency and sleep debt. An ideal sleep latency period also lays the foundation for a solid night's sleep. Tetra Images / Getty Images Sleep Latency's Relation to Sleep Efficiency Sleep latency is related directly to sleep efficiency. If an individual spends the majority of the time they are in bed during an evening actually asleep, then they are considered to be sleep efficient. However, if an individual spends a lot of the time they are in bed not actually asleep, but trying to sleep, then that is not considered to be sleep efficient. A sleep efficiency of 85 percent is considered to be normal, while a sleep efficiency anywhere above 90 percent is considered to be very good. A sleep efficiency lower than 85 percent is considered to be poor. Sleep latency relates directly to sleep efficiency, because if a person is able to fall asleep quickly, they are more likely to have an efficient sleep. If a person has ideal sleep latency, they are likely to have good sleep efficiency as well, since the two go hand in hand. Sleep Latency and the Sleep Cycle An ideal sleep latency lays the foundation for a solid night's sleep, which occurs in two basic states throughout the night. The two stages of sleep that occur throughout the night are rapid eye movement sleep (REM) and non-rapid eye movement sleep (NREM). REM sleep is a deeper form of sleep than most NREM sleep; however, both states of sleep are directly impacted by sleep latency. If an individual has good sleep latency and is able to fall asleep within a reasonable amount of time, they will have a better chance of progressing through the stages of sleep comfortably and, in turn, enjoy a deep sleep. The Impact of Sleep Debt on Sleep Latency Sleep latency also relates directly to sleep debt, which is the overall effect of not getting enough sleep. Sleep debt can accumulate over time and, in turn, lead to mental and physical fatigue. Sleep debt has a direct impact on sleep latency, since those who are extremely tired or have a lot of sleep debt will likely fall asleep quicker than someone who is better rested and does not have any sleep debt. There are many factors that determine an individual's sleep latency, and overall sleep debt is a big one. 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. Was this page helpful? Thanks for your feedback! Tossing and turning night over night can have a big impact on your quality of life. Our free guide can help you get the rest you need. Sign up for our newsletter and get it free. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article 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. 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 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 Goel N, Rao H, Durmer JS, Dinges DF. Neurocognitive consequences of sleep deprivation. Semin Neurol. 2009;29(4):320–339. doi:10.1055/s-0029-1237117