What is Sleep Inertia? How to Get Rid of That Morning Grogginess

Tired woman laying in bed.

Do you ever wake up in the morning, and just want to go back to sleep? You hit the snooze button on your alarm a few times to catch a few more minutes of rest, but in the end, it doesn’t help— you probably feel sluggish, scatterbrained, and dependent on your morning cup of joe to perk up afterward. After all that, your morning routine may even feel like a greater task than usual.

This experience is what’s known as sleep inertia. Sleep inertia itself isn’t a bad thing, but it can potentially cause problems if it gets out of control. 

What is Sleep Inertia?

Isaac Newton’s Law of Inertia states that an object in motion will stay in motion unless acted on by an unbalanced force, and an object at rest will remain at rest.

Similarly, sleep inertia is that familiar feeling of wanting to stay asleep after you first wake up. It’s characterized by sleepiness, disorientation, and impaired cognitive performance upon waking. This can occur after a period of long sleep duration, or even after a 30+ minute nap.

The most common symptoms of sleep inertia are:

  • The desire to go back to sleep
  • Reduced cognitive function
  • Impaired focus and attention
  • Impaired spatial memory
  • Grogginess

Sleep inertia typically lasts anywhere between 15 and 60 minutes, but severe sleep inertia can last up to a few hours after waking. This can potentially be a problem at work, especially for shift workers, because sluggish and sleep-deprived workers have a significant decrease in their cognitive performance, which can increase their risk of errors or even injury.

What Causes Sleep Inertia?

Experts aren’t sure why you experience sleep inertia, but one theory states that it’s actually a protective mechanism that helps you get back to sleep after an abrupt awakening.

There are more theories about what may cause sleep inertia. Among them include:

  • Increased levels of delta waves in your brain: Delta waves are linked to deep sleep. People with sleep inertia have higher levels of delta waves, and fewer beta waves, which are associated with wakefulness.
  • Reduced blood flow to your brain: It may take a little time for your brain’s blood flow to increase after you wake up.
  • Slower brain reactivation: Some parts of the brain— such as the prefrontal cortex, which is responsible for executive function— may reactivate more slowly than others as you awaken.
  • Increased adenosine levels: Adenosine is a nucleic acid in your brain that is key for sleep and wakefulness— when you wake up, adenosine levels in your brain should be lower to help you feel awake and energized. Higher levels of adenosine from periods of sleep deprivation could potentially cause sleep inertia.

Factors That Can Make Sleep Inertia Worse

The severity of your sleep inertia can depend on a few factors:

  • How sleep deprived you are: Consecutive nights of sleep deprivation can increase the duration of sleep inertia because of how your body adjusts to functioning in a sleep-deprived state. This can include trying to cram more slow wave sleep into the decreased time you’re asleep, instead of several hours before waking— when it normally occurs.
  • Your circadian rhythm: If you wake up closer to the times when your circadian rhythm is trying to prepare you for sleep, you’re more likely to experience more sleep inertia. This can happen if you nap too late or for too long during the day.
  • Your chronotype: Your chronotype helps determine your ideal sleep schedule. If you’re fighting your chronotype and sleeping against your body’s natural sleep cycle, you’re more likely to feel groggy throughout the day. Don’t know your chronotype? Check out my chronoquiz.

Disorders Caused by Sleep Inertia

Sleep inertia can be worsened by sleep disorders like shift work sleep disorder and obstructive sleep apnea. But sleep inertia itself can also cause sleep disorders.

Idiopathic Hypersomnia

One sleep disorder that can be caused by sleep inertia is idiopathic hypersomnia. Idiopathic hypersomnia causes you to be excessively sleepy during the day, even after a good night’s sleep or a nap. Your symptoms could potentially occur at any time, even while driving or at work, which can be dangerous.

Symptoms of idiopathic hypersomnia include:

  • Excessive daytime sleepiness
  • Brain fog
  • Sleep attacks, or falling asleep without warning

This condition shares these symptoms with narcolepsy, but they’re not the same disorder. Narcolepsy is caused by disruption to your brain’s sleep-wake cycle, often because of low levels of a chemical called hypocretin. However, narcolepsy may be a cause of idiopathic hypersomnia, and the diagnosis process for both is very similar.

Sleep Drunkenness

Sleep drunkenness, also known as confusional arousal, is a type of parasomnia, or unusual behavior that occurs while you’re sleeping or waking up. Sleep drunkenness is a result of sleep inertia that happens while your brain tries to transition between sleeping and wakefulness.

When this happens, your mind isn’t fully awake, but your body is up and moving. You may even appear drunk or intoxicated— hence the name. This can last for a few minutes or up to an hour.

It’s not a cause for alarm if it happens rarely, but if it happens frequently, it’s vital to seek treatment. People who are sleep drunk may be much more likely to harm themselves or others in this state.

Sleep inertia at best can be an inconvenient occurrence, but at its most severe, it and its associated disorders can cause you, your body, and possibly others, real harm. So how can you put a stop to sleep inertia and take on the day with more energy?

How to Get Rid of Sleep Inertia and Feel Refreshed in the Morning

Here are my 7 tips to prevent or get rid of sleep inertia and seize the day.

1. Take a Short Nap During the Day

Emphasis on the short nap here. You should aim for a 20 to 30-minute power nap for best results.

Like I said above, napping for too long can make you more likely to wake up while your circadian rhythm is preparing you to sleep, which can make sleep inertia worse. You can also drink a cup of coffee before a power nap to prevent you from falling into deeper sleep stages and helping you feel more alert once you wake up. Speaking of coffee…

2. Drink a Caffeinated Beverage

How many of you reach for a cup of coffee or tea first thing in the morning to help you wake up? Caffeine’s stimulant effect is well known, especially in how it makes you feel more awake if you’re struggling to keep your eyes open. This is also why caffeine is effective in reducing sleep inertia.

Sleep inertia can be caused by increased adenosine levels in the brain, which can make you tired. Caffeine works by blocking adenosine receptors in the brain, increasing alertness and wakefulness.

Just be careful to avoid caffeine at least six hours before bed. Too much caffeine during the day— or consuming it too close to bed— can reduce your total sleep time by over 40 minutes and throw off your sleep schedule.

3. Improve Your Sleep Environment

If your bedroom isn’t the perfect environment to sleep in, it’s only natural that your sleep will suffer. Here are a few changes you can make around your bedroom to make it even more conducive to a good night’s sleep.

  • Put new sheets on your bed, or consider a new mattress if yours is getting old or uncomfortable. Upgrading your bedding or mattress can help increase your sleep quality and reduce any aches and pains you may also feel when you wake up.
  • If ambient light from outside keeps you awake or wakes you up too early, try using blackout curtains. Alternatively, an eye mask, such as the Manta Sleep Eye Mask, can block out all ambient light and help you sleep more comfortably.
  • Your bedroom temperature is very important to your sleep quality. 65 to 67 degrees is ideal, but you can adjust your thermostat to see what works best for you. If you share the bed with a sleep partner, consider using either extra layers if you sleep cold, or the ChiliSleep system if you and your partner have different sleep temperature needs.
  • A lot of alarm clocks are loud and can startle you awake, which can make you feel antsy and disoriented. Consider a different alarm that will wake you up gently and gradually, instead of suddenly.

4. Don’t Neglect Your Sleep Hygiene

Your sleep hygiene routine— or lack thereof— can make or break how well you sleep each night. To sleep well each night and wake up refreshed in the morning, consider these sleep hygiene tips:

  • Follow a consistent sleep schedule, especially one that matches your chronotype. Once you know your desired bedtime and wake-up time, stick to these times every single day. That consistency will help your body be ready to sleep or be awake at those designated times, making it much easier to get the rest you need.
  • Avoid electronic devices and screens before bed. The blue light they emit can hinder your brain’s natural melatonin production, which makes it harder to fall asleep on time or sleep through the night. Ideally, you want to stop using your devices at least 60 to 90 minutes before bed for best results.
  • Practice relaxation techniques before bed, such as yoga, breathing exercises, meditation, or taking a warm bath. Relaxing your body and your mind will help sleep come easier, and prevent sleep inertia from making your mornings difficult.

5. Try Aromatherapy

Aromatherapy is the ancient practice of using essential oils for medicinal purposes. Certain essential oils can not only promote sleep, but can also relieve stress, reduce pain, and regulate your mood. Some of my favorites include:

  • Lavender
  • Jasmine
  • Rose
  • Geranium
  • Vanilla
  • Citrus

You can use a diffuser to disperse the oil’s scents into the air, or you can add it to your warm bath, or even directly onto pressure points for a light massage. Make sure you’re using a diluted oil for the last one though— undiluted essential oils can irritate your skin. You can make your own diluted oil solution by mixing your essential oil of choice with a carrier oil like olive oil or vegetable oil.

6. Exercise

30 minutes of moderate exercise per day can do wonders for your rest. Some of the benefits that exercising has on sleep include:

  • Increased time spent in deep sleep, the most restorative sleep stage
  • Increased sleep duration
  • Higher sleep quality
  • Stress relief

You don’t have to do anything intense— even just walking or riding your bicycle for 30 minutes a day will help keep you healthy and sleeping well. Just make sure you do it at least 4 hours before bed. Exercising too close to bedtime can keep you awake and prevent you from getting a full night’s sleep.

7. Get Tested for Sleep Disorders

Even if you make the positive changes you need to improve your sleep, it’s still possible that a sleep disorder can ruin your rest. If you still struggle with sleep inertia and daytime sleepiness, it’s important to get in touch with your doctor or a sleep expert to get tested for sleep disorders.

Along with sleep inertia, symptoms to keep an eye out for can include:

  • Loud snoring
  • Taking more than 30 minutes to fall asleep each night
  • Waking up too early in the morning

Remember, feeling a little groggy first thing in the morning is normal. But if you feel exhausted for an extended period each morning, even after a good night’s sleep, then something is clearly not right. Don’t let sleep inertia ruin your day.

Your resting body should stay at rest during the night, but once morning arrives, it’s important for your body to keep in motion until it’s time to go to bed. It’s the Law of Inertia.

Sweet Dreams,

Michael J. Breus, PhD, FAASM

The Sleep Doctor

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Michael Breus, Ph.D - The Sleep Doctor is a Diplomate of the American Board of Sleep Medicine and a Fellow of The American Academy of Sleep Medicine and one of only 168 psychologists to pass the Sleep Medical Specialty Board without going to medical school. Dr. Breus is a sought after lecturer and his knowledge is shared daily in major national media worldwide including Today, Dr. Oz, Oprah, and for fourteen years as the sleep expert on WebMD. Dr. Breus is the bestselling author of The Power of When, The Sleep Doctor’s Diet Plan and Good Night!

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