/ How Sleep Works / Sleep Inertia: How to Combat Morning Grogginess
Danielle Pacheco Staff Writer
Danielle Pacheco
Staff Writer
Danielle is originally from Vancouver, BC, where she has spent many hours staring at her ceiling trying to fall asleep. Danielle studied the science of sleep with a degree in psychology at the University of British Columbia
Want to read more about all our experts in the field?
Dr. Anis Rehman Internal Medicine Physician
Dr. Anis Rehman
Internal Medicine Physician
Dr. Rehman, M.D., is a board-certified physician in Internal Medicine as well as Endocrinology, Diabetes, and Metabolism.
Want to read more about all our experts in the field?
Fact-Checked
Sleep Foundation
Fact-Checking: Our Process
The Sleep Foundation editorial team is dedicated to providing content that meets the highest standards for accuracy and objectivity. Our editors and medical experts rigorously evaluate every article and guide to ensure the information is factual, up-to-date, and free of bias.
The Sleep Foundation fact-checking guidelines are as follows:
- We only cite reputable sources when researching our guides and articles. These include peer-reviewed journals, government reports, academic and medical associations, and interviews with credentialed medical experts and practitioners.
- All scientific data and information must be backed up by at least one reputable source. Each guide and article includes a comprehensive bibliography with full citations and links to the original sources.
- Some guides and articles feature links to other relevant Sleep Foundation pages. These internal links are intended to improve ease of navigation across the site, and are never used as original sources for scientific data or information.
- A member of our medical expert team provides a final review of the content and sources cited for every guide, article, and product review concerning medical- and health-related topics. Inaccurate or unverifiable information will be removed prior to publication.
- Plagiarism is never tolerated. Writers and editors caught stealing content or improperly citing sources are immediately terminated, and we will work to rectify the situation with the original publisher(s)
- Although Sleep Foundation maintains affiliate partnerships with brands and e-commerce portals, these relationships never have any bearing on our product reviews or recommendations. Read our full Advertising Disclosure for more information.
Table of Contents
Table of Contents
- What Is Sleep Inertia?
- How Long Does Sleep Inertia Last?
- How to Get Rid of Sleep Inertia
Key Takeaways
- Sleep inertia is the groggy feeling upon waking, caused by abrupt disruption of sleep.
- Sleep inertia can briefly impair cognitive and physical function before fading as you gain alertness.
- Consistent wake-up times, natural light exposure, and gentle alarms can help reduce morning sleep inertia.
- A sleep doctor can determine if a sleep disorder is causing more severe sleep inertia.
Sleep is imperative to health and wellness. However, some people experience residual grogginess upon waking, even after receiving adequate sleep. This phenomenon is known as sleep inertia, and is particularly common in those with alternative sleep schedules. Sleep inertia can negatively impact essential cognitive functions, such as reaction time and decision making.
We highlight the causes, symptoms, and diagnostic criteria of sleep inertia, and how to mitigate its negative effects and get quality sleep.
Is Your Troubled Sleep a Health Risk?
A variety of issues can cause problems sleeping. Answer three questions to understand if it’s a concern you should worry about.
Please select all options
What Is Sleep Inertia?
Sleep inertia is the feeling of grogginess, disorientation, drowsiness, and cognitive impairment that immediately follows waking Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source . The biological reason for sleep inertia is unknown. However, researchers hypothesize that sleep inertia is a protective mechanism Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source that helps maintain sleep during moments of unwanted wakings.
Regardless of its biological basis, sleep inertia can impact the safety and well-being of people who work long, frequently changing hours or shift work. Medical professionals who work rotating shifts or are on call regularly have a significant decrease in cognitive alertness Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source and performance. At least 16% of U.S. employees engage in shift work Trusted Source U.S. Bureau of Labor StatisticsThe Bureau of Labor Statistics measures labor market activity, working conditions, price changes, and productivity in the U.S. economy to support public and private decision making.View Source . As a result, these workers might experience slowed reaction times and decreased cognitive alertness at work that increase the chance of work-related injuries.
Symptoms of Sleep Inertia
The most common symptom of sleep inertia is grogginess, but people are also likely to experience impaired cognitive ability, visual attentions, and spatial memory. The symptoms of sleep inertia are most noticeable upon waking from a lengthy sleep period or naps over 30 minutes Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source , but fade over time.
Causes of Sleep Inertia
The exact cause of sleep inertia is unknown, but there are three common theories explaining sleep inertia.
Some research suggests that sleep inertia is caused by an increase in delta waves Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source in the posterior part of the brain. Delta waves, or slow waves, are most commonly seen in the non-rapid eye movement (NREM) stage of sleep. Delta waves are more likely to increase after periods of sleep deprivation or loss. Sleep inertia may occur when the brain has not yet reduced delta waves in preparation for waking up, or is suddenly awoken during NREM sleep.
Adenosine, a nucleic acid compound found in the brain, plays a pivotal role in sleep and wakefulness. Upon waking, adenosine levels should be low. Research suggests that sleep inertia could be caused by high levels of adenosine Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source upon waking.
The body’s blood flow to the brain follows a pattern corresponding to sleep cycles, increasing or decreasing Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source depending on the stage of sleep. Chronic fatigue syndrome (CFS) is linked to reduced cerebral blood flow. CFS symptoms are similar to sleep inertia, and it may be that a reduction in blood flow upon waking results in sleep inertia symptoms. However, more research needs to be done to support this concept.
How Long Does Sleep Inertia Last?
Sleep inertia generally lasts for 15 to 60 minutes Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source , but may last for up to a few hours after waking.
Sleep inertia itself is not a sleep disorder, but people with certain sleep disorders are more likely to experience more severe or longer lasting sleep inertia. If you notice that you are feeling groggy or fatigued throughout the day, consider talking to your doctor about taking part in a sleep study, called polysomnography. A sleep study can help your doctor determine if any underlying disorders are impacting your sleep and causing more severe sleep inertia.
Keeping a sleep journal may also provide your doctor insight into your sleeping patterns. Record times you sleep, as well as how you feel when you wake and any symptoms you experience. It can also be useful to check in with a partner for insight into your sleep and wake patterns. If you can pinpoint a trigger for your sleep inertia, like excessive caffeine use or inconsistent sleeping patterns, it may help to make lifestyle adjustments and record any change.
How To Get Rid of Sleep Inertia
Although the exact cause of sleep inertia is unknown, there are ways you can adjust your lifestyle to facilitate better sleep and increase wakefulness. Additionally, engaging in a good sleep hygiene routine can help you obtain better sleep and may prevent sleep inertia.
- Pick the right bedding: Find the best mattress and bedding to feel comfortable at night. Research has found that those who upgraded their mattress and bedding experienced less pain and an increase in sleep quality.
- Avoid alcohol and smoking: Drinking alcohol in excess can impact the quality of your sleep. Smoking has been associated with sleeping problems, including trouble falling asleep and low sleep satisfaction.
- Napping: Sleeping for a short period of time during a break at work may help reduce sleep inertia. Naps are a common way people fit extra sleep into their day. Make sure your naps are no longer than 30 minutes, as this may increase your risk of experiencing sleep inertia and difficulty falling asleep at night.
- Caffeine intake: Reaching for a cup of coffee or energy drink may help you feel more awake in the morning. Caffeine works by blocking adenosine receptors in the brain, which increases wakefulness and alertness. However, too much caffeine may negatively impact your sleep.
- Light restriction: Keeping your sleep and wake cycles in alignment with the natural rise and fall of the sun may help reduce sleep inertia. Studies show that artificial light can impact the body’s natural circadian rhythm and disrupt sleep Trusted Source National Library of Medicine, Biotech InformationThe National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information.View Source when exposed later in the day. Adjusting the light in your bedroom with blackout curtains may help you get more restful sleep.
- Temperature adjustments: Sleeping in a room that is too hot prevents your body from cooling before sleep, resulting in fatigue. Try adding a quiet fan to your room or sleep with lighter, breathable blankets. During summer, consider investing in a small air conditioner unit or lightweight pajamas.
- Gentle waking: Many alarm clocks can be jarring and loud, which could exacerbate feelings of confusion or grogginess upon waking. Try opting for a smart alarm clock app that registers when you are in a light state of sleep. Or, try a sunrise alarm that wakes you with gradually increasing light and gentle sounds.
Written By
Danielle Pacheco,Staff Writer
Danielle is originally from Vancouver, BC, where she has spent many hours staring at her ceiling trying to fall asleep. Danielle studied the science of sleep with a degree in psychology at the University of British Columbia
Medically Reviewed by
Dr. Anis Rehman,Internal Medicine PhysicianMD
Dr. Rehman, M.D., is a board-certified physician in Internal Medicine as well as Endocrinology, Diabetes, and Metabolism.
References
10 Sources
Burke, T. M., Scheer, F., Ronda, J. M., Czeisler, C. A., & Wright Jr., K. P. (2015). Sleep inertia, sleep homeostatic and circadian influences on higher-order cognitive functions. Journal of Sleep Research, 24(4), 364–371.
https://pubmed.ncbi.nlm.nih.gov/25773686/Hilditch, C. J., & McHill, A. W. (2019). Sleep inertia: Current insights. Nature and Science of Sleep, Volume 11, 155–165.
https://pubmed.ncbi.nlm.nih.gov/31692489/Basner, M., Dinges, D. F., Shea, J. A., Small, D. S., Zhu, J., Norton, L., Ecker, A. J., Novak, C., Bellini, L. M., & Volpp, K. G. (2017). Sleep and alertness in medical interns and residents: An observational study on the role of extended shifts. Sleep, 40(4), zsx027.
https://pubmed.ncbi.nlm.nih.gov/28329124/Bureau of Labor Statistics. (2019, September). Job Flexibilities and Work Schedules Summary. (USDL-19-1691).
https://www.bls.gov/news.release/flex2.nr0.htmRuggerio, J. S., & Redeker, N. S. (2014). Effects of napping on sleepiness and sleep-related performance deficits in night-shift workers: A systematic review. Biological Research for Nursing, 16(2), 134–142.
https://pubmed.ncbi.nlm.nih.gov/23411360/Marzano, C., Ferrara, M., Moroni, F., & De Gennaro, L. (2011). Electroencephalographic sleep inertia of the awakening brain. Neuroscience, 176, 308–317.
https://pubmed.ncbi.nlm.nih.gov/21167917/Van Dongen, H. P., Price, N. J., Mullington, J. M., Szuba, M. P., Kapoor, S. C., & Dinges, D. F. (2001). Caffeine eliminates psychom*otor vigilance deficits from sleep inertia. Sleep, 24(7), 813–819.
https://pubmed.ncbi.nlm.nih.gov/11683484/Hajak, G., Klingelhöfer, J., Schulz-Varszegi, M., Matzander, G., Sander, D., Conrad, B., & Rüther, E. (1994). Relationship between cerebral blood flow velocities and cerebral electrical activity in sleep. Sleep, 17(1), 11–19.
https://pubmed.ncbi.nlm.nih.gov/7910702/Hilditch, C. J., Dorrian, J., & Banks, S. (2016). Time to wake up: Reactive countermeasures to sleep inertia. Industrial Health, 54(6), 528–541.
https://pubmed.ncbi.nlm.nih.gov/27193071/Chang, A. M., Santhi, N., St Hilaire, M., Gronfier, C., Bradstreet, D. S., Duffy, J. F., Lockley, S. W., Kronauer, R. E., & Czeisler, C. A. (2012). Human responses to bright light of different durations. The Journal of physiology, 590(13), 3103–3112.
https://pubmed.ncbi.nlm.nih.gov/22526883/
Learn More About How Sleep Works
Can You Learn a Language While Sleeping?
ByJay Summer June 11, 2024
How to Become a Morning Person
ByDanielle Pacheco May 13, 2024
How Much Sleep Do You Need?
ByEric Suni May 13, 2024
How Memory and Sleep Are Connected
ByDanielle Pacheco May 9, 2024
What Causes Excessive Sleepiness?
ByDanielle Pacheco May 8, 2024
What Causes Restless Sleep?
ByEric Suni May 8, 2024
Biphasic Sleep: What It Is And How It Works
BySarah Shoen April 26, 2024
Polyphasic Sleep: Benefits and Risks
ByDanielle Pacheco April 26, 2024
REM Rebound: Causes and Effects
ByJay Summer April 11, 2024
REM Rebound: Causes and Effects
ByJay Summer April 11, 2024
Do Moon Phases Affect Your Sleep?
ByJay Summer April 5, 2024
Why Do We Need Sleep?
ByLucy Bryan April 5, 2024
Alpha Waves and Sleep
ByJay Summer April 1, 2024
How Age Affects Your Circadian Rhythm
ByDanielle Pacheco March 19, 2024
How Is Sleep Different For Men and Women?
ByLucy Bryan March 19, 2024
Circadian Rhythm
ByLucy Bryan March 15, 2024
Chronotypes: Definition, Types, & Effect on Sleep
ByDanielle Pacheco March 1, 2024
Sleep Drive and Your Body Clock
ByEric Suni March 1, 2024
8 Health Benefits of Sleep
ByJay Summer February 29, 2024
Daylight Saving Time: Everything You Need to Know
ByDanielle Pacheco February 27, 2024
How To Get a Good Night’s Sleep in a Hotel
ByDanielle Pacheco February 22, 2024
Does Napping Impact Your Sleep at Night?
ByDanielle Pacheco February 2, 2024
Does Daytime Tiredness Mean You Need More Sleep?
ByLucy Bryan February 2, 2024
Why Do I Wake Up at 3 am?
ByJay Summer January 19, 2024
Sleep Debt: The Hidden Cost of Insufficient Rest
ByRob Newsom January 16, 2024
Sleep Satisfaction and Energy Levels
ByDanielle Pacheco December 22, 2023
How Sleep Works: Understanding the Science of Sleep
ByEric Suni December 22, 2023
What Makes a Good Night's Sleep
ByDanielle Pacheco December 22, 2023
What Happens When You Sleep?
ByEric Suni December 22, 2023
Sleep and Social Media
ByRob Newsom December 22, 2023
Orexins
ByRob Newsom December 22, 2023
Adenosine and Sleep: Understanding Your Sleep Drive
ByLucy Bryan December 14, 2023
Oversleeping
ByAustin Meadows December 8, 2023
Hypnagogic Hallucinations
ByJay Summer December 8, 2023
Hypnopompic Hallucinations
ByJay Summer December 8, 2023
What All-Nighters Do To Your Cognition
ByJay Summer December 1, 2023
Long Sleepers
ByEric Suni November 13, 2023
How to Wake Up Easier
ByJay Summer November 8, 2023
Sleep Spindles
ByJay Summer October 23, 2023
Does Your Oxygen Level Drop When You Sleep?
ByJay Summer October 18, 2023
100+ Sleep Statistics
ByEric Suni September 26, 2023
Short Sleepers
ByEric Suni June 2, 2023
How Electronics Affect Sleep
ByDanielle Pacheco June 2, 2023
Myths and Facts About Sleep
ByEric Suni June 1, 2023
What’s the Connection Between Race and Sleep Disorders?
ByEric Suni June 1, 2023
Sleep Latency
ByDanielle Pacheco January 18, 2023
Microsleep: What Is It, What Causes It, and Is It Safe?
ByJay Summer January 6, 2023
Light Sleeper: What It Means and What To Do About It
ByDanielle Pacheco January 3, 2023
Load More Articles