How Does Sleep Inertia Make it Hard to Wake and What Treatments Help?

Morning Sleepiness Worsened by Sleep Deprivation, Other Sleep Disorders

A woman experiences sleep inertia to stay asleep in the morning past her desired wake time
A woman experiences sleep inertia to stay asleep in the morning past her desired wake time. Getty Images

It is something that you may experience nearly every morning when you wake up: that compelling, nearly irresistible desire to go back to sleep. Even after you get up, you may feel groggy and ready to return to bed. This is called sleep inertia, and it can make it very difficult to wake up and function at your best. What are the most common symptoms of sleep inertia and how does it make it hard to wake up?

What are the best ways to avoid it and what are the most helpful fixes and treatments?

The History and Science of Sleep Inertia

Sleep inertia was first described among U.S. Air Force pilots in the 1950s. Pilots were often stationed in the cockpits of their planes, ready to take off at a moment’s notice. It was found that if these pilots were asleep when the alarm sounded, they’d awaken and make simple mistakes, their minds still groggy from being asleep.

Inertia refers to the concept in physics that an object naturally resists changes in its state of motion. A ball rolling down a hill will continue to roll, and one at rest tries to remain at rest, unless other forces are applied to alter their state. As the concept of inertia is applied to sleep, when you are asleep, your brain would just as soon stay asleep.

What Are the Symptoms of Sleep Inertia?

This phenomenon leads to sleepiness and cognitive and psychomotor impairment that can occur immediately after awakening.

Though most of us aren’t flying fighter jets, we may be impaired in our ability to make decisions or perform complex activities like driving a car, and we may have a feeling of profound mental grogginess. The strong desire to return to sleep may cause just that to occur.

What Causes Sleep Inertia?

These symptoms most commonly will occur with abrupt awakenings, especially from deep or slow-wave sleep in the first part of the night, or when sleep duration is insufficient.

Sleep deprivation can make it difficult to wake. It may be more likely if an awakening is timed earlier than normal (such as setting an alarm extra early to go to the airport to catch a flight). The symptoms may persist for minutes up to an hour or more after awakening. Though it is not fully understood, one theory suggests that sleep inertia is caused by the build up of a neurotransmitter called adenosine within the brain during non-REM sleep leading to feelings of sleepiness.

It may be worsened in sleep disorders such as sleep apnea and delayed sleep-wake phase disorder. Sleep apnea disturbs the quality of sleep as sleep is fragmented to restore breathing. Delayed sleep-wake phase disorder is characterized by insomnia with a delayed natural ability to fall asleep. In the morning, it is difficult to wake. Idiopathic hypersomnia, or sleepiness of an unknown cause, may also contribute to sleep inertia.

The Best Fixes and Treatments for Sleep Inertia

It is important to optimize both sleep quantity—obtaining sufficient hours of sleep to meet your sleep needs—as well as sleep quality. Any coexisting sleep disorders, such as sleep apnea, should be effectively treated. In addition, some people benefit from using an alarm that wakes the person within a range of times and will prompt an awakening when light sleep or movements are noted.

Finally, morning sunlight can be another effective to wake feeling more refreshed. As a last resort, caffeine and other interventions such as prescription stimulant medications may help to promote wakefulness in the morning.

If you continue to have problems with sleep inertia, speak with your doctor about getting further sleep evaluation including a possible sleep test.


American Academy of Sleep Medicine. International classification of sleep disorders, 3rd ed. Darien, IL: American Academy of Sleep Medicine, 2014.

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