What Is Sleep Latency?

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 rest.

If you take longer than that to fall asleep, it can affect your sleep efficiency, or the percentage of time spent asleep while in bed. Alternatively, if you nod off as soon as your head hits the pillow, it could be a sign that 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 issues nodding off.

Significance of Sleep Latency

Sleep latency is important because it can be an indicator of whether you're getting enough sleep. Not getting enough sleep can make you feel tired and moody the next day.

Over time, a sleep deficit can start to have serious effects on your concentration, how you feel, and your ability to accomplish daily tasks. It can also raise your risk of developing health conditions, such as:

• Diabetes
• Heart disease
• Obesity
• Infections
• Depression
• Anxiety

When Sleep Latency Is Too Long

Long sleep latency means that it can take more than 20 minutes to fall asleep at night. A variety of factors can cause long sleep latency, such as taking frequent naps and experiencing chronic pain.

A long sleep latency can sometimes be a sign of a more serious problem, such as insomnia (trouble falling or staying asleep). Risk factors for insomnia include anxiety, an inactive lifestyle, travel, and a variety of other factors.

You might become frustrated if it takes you a while to fall asleep. If you have to wake up at a certain time and have a long sleep latency, you may not get as much sleep as you need. You may also cycle through fewer stages of sleep.

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 overall restoration.

When Sleep Latency Is Too Short

Short sleep latency means that you fall asleep almost immediately. This is often a sign of sleep debt, which is the overall effect of not getting enough sleep. Sleep debt can accumulate over time.

Drinking alcohol may also lower sleep latency, as can certain conditions, such as narcolepsy and idiopathic hypersomnia. Both of those conditions involve excessive daytime drowsiness, but idiopathic hypersomnia also interferes with the sleep cycle.

Measuring Sleep Latency

A healthcare provider may recommend a test to measure sleep latency if they suspect you may have a sleep disorder. There are three common ways to measure sleep latency: a polysomnogram, multiple sleep latency test, and maintenance of wakefulness test.

Polysomnogram

The polysomnogram is an overnight sleep study done at a sleep laboratory or, sometimes, at home. It is used to diagnose several conditions, including sleep apnea.

The test simply involves sleeping with sensors attached to your body that measure your heart rate, breathing, and brain waves. In the morning, you'll be asked to fill out a questionnaire about your sleep experience.

A polysomnogram can detect how quickly you enter into deep stages of sleep to determine whether your sleep latency is long, short, or ideal. A healthcare provider will reach out with results once they have been interpreted.

Multiple Sleep Latency Test

The Multiple Sleep Latency Test (MSLT) is a test that evaluates how quickly you fall asleep for a daytime nap after a night of sleep. This test is used to diagnose narcolepsy and idiopathic hypersomnia, and is typically done the day after getting a polysomnogram.

MSLTs are performed in a healthcare setting. Sensors that measure your sleep latency and sleep cycle are placed on your head. You are then given the chance to take five naps, each spaced two hours apart. You are woken up 20 minutes into each nap.

A healthcare provider will review the results and contact you to discuss a treatment plan.

Maintenance of Wakefulness Test

The goal of this test is to see how long you can stay awake for a certain period of time. It's given after you've already started treatment for a sleep disorder. It can measure whether you're too sleepy to perform tasks such as driving or operating dangerous equipment.

Sensors will be placed on your head before the test begins. Then you'll be given four trials spaced two hours apart where you lay in a dark room and try not to fall asleep.

How to Improve Sleep Latency

If you're having sleep issues, paying attention to your sleep latency is a helpful way to get to the root of the problem. A healthcare provider can help you pinpoint the cause of your sleep latency issues so that the problem can be treated.

For example, if you can't fall asleep because of chronic pain, treating the underlying pain may help you fall asleep more quickly. If anxiety is keeping you awake, strategies such as exercising more or meditating may curb it so that you can have a shorter sleep latency.

When sleep latency is too short, it's usually due to sleep deprivation. Changing your lifestyle or treating the issue with medication or another medical intervention may improve your quality of sleep and shorten sleep latency.

When to See a Healthcare Provider

While there are general guidelines for ideal sleep latency, having a short or long sleep latency doesn't necessarily mean you have a health issue. However, you may want to reach out to a healthcare provider if you're experiencing symptoms aside from abnormal sleep latency, including:

• Fatigue that interferes with work or another daytime activity
• Problems with concentration or memory
• Waking up throughout the night
• Depression

When evaluating you, a healthcare provider will consider sleep latency along with your symptoms and other aspects of sleep. You may be asked to fill out a questionnaire, such as the Epworth Sleepiness Scale or the Pittsburgh Sleep Quality Index.

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.