An Overview of Sleep Inertia

When Morning Sleepiness Is Worse Than Usual

It is something that you may experience nearly every morning when you wake up—that compelling, nearly irresistible desire to go back to sleep. But, even after you get up, you may still 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. 

Woman and cat laying in bed
Dornveek Markkstyrn / Getty Images

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.


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.

For example, it may be difficult to drive a car safely in the morning immediately after waking. We may also have a feeling of profound mental grogginess. And the strong desire to return to sleep may cause just that to occur, leading to irresistible sleep attacks.


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, too. It may be even 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.

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 that leads 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. It is often associated with snoring, gasping or choking episodes, witnessed pauses in breathing, frequent urination at night, teeth grinding, insomnia including early morning awakenings, and other symptoms.

Delayed sleep-wake phase disorder is characterized by insomnia with a delayed natural ability to fall asleep at the beginning of the night. It often starts in teenagers but may persist throughout life. An affected person may not fall asleep until 2 A.M. or later. And, in the morning, it is difficult to wake. This may compel a night owl to sleep in and any attempt at waking earlier may be fruitless. Sleep deprivation may lead to other symptoms as well. (Idiopathic hypersomnia, or sleepiness of an unknown cause, may also contribute to 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. Most adults need seven to nine hours of sleep nightly to feel rested. Older adults may get by on a little less sleep, perhaps needing no more than eight hours.

Any co-existing sleep disorders, such as sleep apnea, should be effectively treated. These treatments will enhance sleep quality which, in turn, will decrease morning sleepiness and sleep inertia. In addition, some people benefit from using an alarm that wakes them within a range of times and will prompt an awakening when light sleep or movements are noted.

Exposure to morning sunlight can be another effective method to wake feeling more refreshed. It helps to initiate the circadian alerting signal. As a last resort, caffeine and other interventions, such as prescription stimulant medications like Nuvigil and Provigil, may help to promote wakefulness in the morning.

A Word From Verywell

If you continue to have problems with sleep inertia, speak with your healthcare provider about getting further evaluation, including a possible sleep test. If you are already getting sufficient hours of rest, treating a hidden sleep disorder may provide the extra relief you need to wake up feeling your best.

Frequently Asked Questions

  • How can you wake up earlier?

    It helps to get a good night's sleep, so try turning off your laptop, phone, or anything with a screen at least an hour before bed. To help wake up in the morning, open the curtains to let in sunlight. Schedule time for exercise to help you feel more energized, whether it's taking a walk or doing yoga.

  • How can you wake up someone else?

    One method to try: Play their favorite song. In a 2020 study, people felt they were able to wake up more easily with music playing.

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  5. McFarlane S, Garcia J, Verhagen D, Dyer A. Alarm tones, music and their elements: Analysis of reported waking sounds to counteract sleep inertiaPLoS One. 2020;15(1):e0215788. doi:10.1371/journal.pone.0215788

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