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What Is Sleep Inertia? Symptoms, Causes, and Treatments

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We’ve all been there before. The alarm clock suddenly blares or sunlight hits our face and we wake in a mental fog. Crawling out of bed, the world is fuzzy and that drowsy feeling makes even the simplest tasks feel like a chore. For some this happens once in a blue moon; for others it’s continuous.

If you’ve ever experienced that feeling of grogginess and disorientation upon waking, chances are you’ve encountered sleep inertia. Though it may not last long, sleep inertia is a common problem that’s solely defined by impaired cognitive and motor performance immediately after waking up.

And while it may seem harmless, those who suffer from severe sleep inertia may be at a higher risk for other problems such as impaired motor dexterity or cognitive performance. In serious cases it can warrant a trip to a sleep specialist.

So what’s there to know about sleep inertia? Why does it occur, and what can we do to treat it? Stay awake for this one and come along for a journey as we take a closer look at sleep inertia.

Sleep Disorders and Sleep Inertia

Perhaps you’ve heard of sleep disorders before. Some well-known sleep disorders include insomnia, sleep apnea, restless leg syndrome, narcolepsy, and even sleep walking. Characterized by changes in sleep patterns that negatively affect your health, sleep disorders are widespread — roughly 40 million Americans suffer from long-term sleep disorders, according to the National Institute of Neurological Disorders and Stroke.

Within the world of sleep disorders are a group of specific sleep disorders known as parasomnias. These involve unwanted events or experiences that occur while you’re falling asleep, sleeping, or waking up. From night terrors to bedwetting to unusual eye movement, parasomnias are widespread and often disruptive in nature. While sleep inertia is not a parasomnia and therefore not defined as a sleep disorder, those who suffer from a parasomnia often experience sleep inertia as well.

Sleep Inertia Causes

Now that we know how sleep inertia is classified amongst other sleep disorders, let’s take a closer at why it occurs in the first place. Of the many reasons you may experience sleep inertia, research has provided us with a few primary possibilities.

Abrupt Awakenings

When your body drifts off to sleep it transitions through stages of the sleep cycle before entering a stage known as deep sleep. In this stage, your body heals, brain waves slow down, and you get the greatest amount of rest, which contributes to how refreshed you feel in the morning.

But sometimes this stage of sleep abruptly ends. Maybe you need to catch an early flight or a loud noise wakes you from slumber. While your body would normally transition out of deep sleep and into light sleep before you wake, an abrupt awakening from deep sleep will generate far more sleep inertia. This is why it can be so painful to wake in the early morning hours after going to bed late or getting only a few hours of shut-eye.

Slower Brain Reactivation

It comes as no surprise that your brain requires a bit of time to warm up in the morning. After all, it was just in a state of rest not long ago. Yet research shows that certain areas of the brain, such as the prefrontal cortex, may take more time to reactivate in the morning. Often these areas of the brain deal with executive and cognitive functions, which explains why decision-making or motor tasks may be difficult until we’ve had a chance to get into the day.

Blood Flow

Some research suggests that cerebral blood flow (blood flow in the brain) slows down as we sleep and therefore takes time to increase in velocity after we’ve woken up.

Symptoms and Effects of Sleep Inertia

The symptoms and effects of sleep inertia vary from person to person but are often rather similar. Chances are you’re experiencing sleep inertia if you feel drowsy, lethargic, or experience morning grogginess. You may also have trouble concentrating or your reaction time may be delayed. With that said, sleep inertia usually subsides within a half hour of waking. It can disappear within 15 minutes for some, but a “full recovery” can take up to two hours.

Diagnosis and Treatment

While sleep inertia doesn’t typically affect you for extended periods of time, some individuals suffer from serious bouts of sleep inertia that may require a professional diagnosis. Diagnosing severe sleep inertia isn’t easy, but a sleep study known as a polysomnography can monitor your sleep patterns in real-time to diagnose specific sleep disorders. An electroencephalogram (EEG) will also be used to monitor the electrical activity of your brain.

A doctor may also ask about other factors that contribute to your sleep inertia such as stress, medications, other sleep disorders, depression, or the shift during which you work. Shift workers covering the night shift are more likely to experience poor sleep quality and suffer from sleep inertia.

If you happen to be diagnosed with severe sleep inertia, fear not. Often a doctor will intervene after determining whether or not you suffer from other sleep disorders. They may also recommend lifestyle changes such as consuming less alcohol or increasing sleep duration. Sleep medicine or sleep supplements such as magnesium may be prescribed to promote sleep at night.

All that said, most people won’t require such forms of intervention. To combat those infrequent bouts of sleep inertia that occur from time to time, simpler measures can be taken.

At-Home Treatment

Treating mild forms of sleep inertia can be done in the comfort of your own home without professional intervention. Below you’ll find a few reactive countermeasures that may help.


Consuming caffeine is a popular means of combating the effects of sleep inertia in an effort to provide that feeling of wakefulness and energy. Despite its overwhelming popularity, you should still make sure to consume caffeine with care. It can easily disrupt your ability to sleep during your regular sleep time, and therefore shouldn’t be used to tackle sleepiness before bed. Consider utilizing caffeine with other natural substances like L-theanine to ensure it doesn’t overload you with energy.


Most of us love a short nap (if time allows), but it’s important to note that the nap itself must be rather short indeed. A nap to combat drowsiness should be between 10 and 20 minutes, and it should take place in the afternoon. Taking a nap to combat prior sleep deprivation also isn’t a healthy idea, as your body desperately needs hours of sleep rather than a brief sleep episode.

Light Exposure

Light exposure is a healthy and natural means of waking your body and mind if you find yourself suffering from sleep inertia. All it takes is a dose of natural sunlight for your body to suppress melatonin levels (the hormone that regulates your sleep-wake cycles) and get you going should grogginess be an issue. It should be noted, however, that only exposure to natural sunlight will do the trick; white light or artificial light isn’t sufficient.

The Subtraction Task

Some individuals utilize what is known as the subtraction task to increase brain activity and reduce the sleep inertia period. Many apps such as Mathe Alarm Clock now offer an alarm clock that can only be turned off after you’ve completed a simple subtraction equation, thus ensuring you’re awake enough to answer the question and get out of bed.

Sleep Schedule Alterations

Consider altering your sleep schedule if you find yourself sleeping at odd hours of the day or night. Your body will naturally follow its own circadian rhythm to try and sleep at night when possible, so don’t fight that sleepy feeling when it arises. Consider utilizing a fitness tracker that also contains a sleep tracker so that you can monitor and adjust your sleep schedule as needed.

Other Remedies

Other simple remedies include splashing water on your face or blasting cold air in an effort to wake up. If you’ve found a healthy countermeasure to get you up, don’t be afraid to use it.

Living With Sleep Inertia

More often than not, sleep inertia is an inconvenience rather than a serious issue. It occurs when we’ve had a rough night’s sleep or need to wake up early to catch a flight. To combat sleep inertia, utilize the concepts above unless your sleep inertia is more severe. Should that be the case, speak with a medical professional to discuss your options. While few of us enjoy the process of waking up, there is a lot you can do to ensure it all goes smoothly.

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