Transparency Disclosure — We may receive a referral fee for products purchased through the links on our site…Read More.

Sleep Inertia: Why Am I so Tired In the Morning?

Disclaimer – Nothing on this website is intended to be a substitute for professional medical advice, diagnosis, or treatment… Read More Here.

If you’re like most people, waking up is not an easy task. After your adrenaline jolting alarm clock summons you from sleep, it still takes a shower, two cups of coffee (okay maybe three), and a good 20-30 minutes before you finally feel awake.

Morning grogginess affects pretty much everyone living in the 21st century at one point or another, but for some folks, it’s a daily struggle. Have you ever wondered why your best friend practically bounces out of bed, perky and cheerful, while it takes you a good hour just to remember your own name? Are you destined to suffer from post-sleep stupor forever?

Apparently, this phenomenon is a real thing and it’s referred to in the medical world as sleep inertia.

 Let’s take a look at what it is and explore some tips and tricks on how to fight it.

What Is Sleep Inertia?

Sleep inertia (SI) is the term used to describe that groggy in-between state when you’re no longer asleep but not quite awake. Humans have likely been experiencing SI since the beginning of time, but it was only given a name in 1976. Before then, it was referred to as “sleep drunkenness”, which I think more accurately describes what it is.  

In physics, ‘inertia’ refers to the resistance of an object to changes in velocity. The Encyclopedia Britannica describes it as the “property of a body by virtue of which it opposes any agency that attempts to put it in motion.” If we apply this to sleep, inertia is the brain’s resistance to waking up.

SI and the Brain

Let’s take a deeper look into the brain to see what causes this disoriented state. While there’s still so much we don’t know about why sleep inertia occurs, research has given us some clues pointing to multiple factors. 

In one study, scientists used brain scans to look at blood flow in the brain during the period of awakening. They discovered that immediately after you wake up, blood flow returns to the brainstem (the area of the brain that oversees basic physiological functions), but it takes 20-30 minutes for blood flow to activate cortical regions like the prefrontal cortex (the area responsible for self-control and decision making). 

One of the most important factors determining the severity of symptoms is the sleep stage that you’re in prior to being woken up.  Humans progress through 4 stages of sleep during a full 90-minute sleep cycle. There are 3 stages of NREM (non-rapid eye movement) sleep and one stage of REM (rapid eye movement) sleep, which is when dreaming occurs.

Stages 1 and 2 are considered lighter stages of sleep, and stage 3 is the deepest, often referred to as slow-wave sleep. During this deep sleep state, the brain produces slow delta waves and is the least responsive to the outside world. According to some research, abrupt awakening during stage 3 produces more SI than any other stage.

Another factor that comes into play is sleep debt. Being chronically deprived of zzz’s increases the amount of time you spend in stage 3, making it more likely that you’ll be in that stage when your alarm clock sends out its infernal sound.

If it feels like your brain keeps pushing the snooze button even though you’re physically out of bed, your body temperature could be the reason why. Normal core body temperature fluctuates throughout the day and night, influencing the circadian rhythm and playing a role in physiological arousal.

Research has found that inertia is worse if you wake when core body temperature is lowest (between 4-6 am) versus when it is highest (early evening hours).

What Are the Symptoms?

In her study entitled, “Waking up is the hardest thing I do all day: Sleep inertia and sleep drunkenness,” Dr. Lynn Marie Trotti describes the main symptoms of SI as “impaired performance, reduced vigilance, and a desire to return to sleep.”

During this period of grogginess and disorientation, even simple tasks can feel complicated. Have you ever shown up to work only to discover that your shirt is buttoned unevenly or you completely forgot to put the garbage out? Memory and the ability to perform basic tasks are two of the many areas that suffer under the influence of SI. 

Most people have learned to deal with this drowsy state by drinking coffee and waiting for the light switch to turn on again in their brains. But for night shift workers like nurses and doctors who are on call or nap on the job, this temporary mental block could lead to serious (even deadly) mistakes. Likewise, for anyone attempting to get behind the wheel, drowsy driving during the early morning hours has resulted in many traffic accidents over the years.

Sleep inertia causes cognitive and psychomotor impairments in areas like alertness, attention, memory, reaction time, and the ability to perform basic mathematical tests. Even after you “feel” awake, your cognitive faculties may not be fully up to speed. 

Read More: How Shift Work Affects the Circadian Rhythm

How Long Does This Last?

This groggy and disoriented state has been known to last anywhere from 1 minute up to 4 hours, but in most cases the symptoms clear within 30 minutes. In people who are chronically sleep-deprived, inertia may last longer because of a greater drive for sleep or because they are more likely to wake during the slow-wave stage.

Post-Nap Grogginess

Cats and dogs aren’t the only ones who like to cuddle up for a midday snooze. Many people enjoy leisurely napping and its many health benefits, but one of the greatest downsides is post-nap grogginess. If you’ve ever tried taking an afternoon nap to curb fatigue only to wake feeling worse than before, sleep inertia could be to blame. 

According to some recent research, the length of nap is an important factor in how groggy you feel when you awaken. Scientists from the University of California, Berkeley and the Lyon Neuroscience Research Center in France measured brain activity in 34 volunteers before and after they took a 45-minute nap using EEG, fMRI, and performance level (mental subtraction). Participants who were woken up during deeper stage 3 slumber had more severe functional disconnectivity between brain networks and took longer to recover than those who were woken up during lighter stage 2 rest.

Based on these findings and some other studies that had similar results, the researchers recommend limiting naps to 25 minutes or less to avoid going into a deep sleep. Otherwise, you would need a 90-minute window to sleep through an entire cycle in order to prevent post-nap inertia.

Some research has found that consuming a small amount of caffeine (a cup of coffee or about 200 mg of caffeine) just prior to taking a nap could help to offset some of the SI that people experience after napping. “Coffee naps” have often been recommended to curb drowsy driving or for short naps during the night shift. Caffeine takes 20-30 minutes to work, so consuming coffee right before a short nap may give it just enough time to kick in and have an alerting effect when you wake up.

Find Out More: Different Types of Naps Explained

Is It Dangerous?

For most people, SI is annoying and may mean you end up leaving the house with two different pairs of shoes on, but beyond embarrassment and some minor inconvenience, the effects are short-lived and shouldn’t pose any harm. That doesn’t mean that sleep inertia is entirely without risk.

Driving while drowsy causes more accidents per year than drugs and alcohol combined. Some of these accidents are because of the driver staying awake too long, but the majority happen in the morning hours when post-sleep grogginess hasn’t worn off. SI decreases reaction times and concentration, and the effects of drowsy driving can be just as dangerous as driving drunk.

Sleep inertia is also a greater concern for shift workers and people who are on-call during night-time hours since they often have to perform critical tasks soon after waking. Physicians, nurses, pilots, and many others may find themselves making life-threatening mistakes shortly after abruptly waking from sleep. 

A study from Australia found that during the first few minutes after waking, decision-making performance was as low as 51% of normal levels. Even after 30 minutes, performance levels remained as low as 20% less than baseline. Some research suggests that SI may impact cognitive performance for up to two hours after waking.

Sleep Inertia and Children

Children may be just as susceptible as adults when it comes to post-sleep grogginess and confusion. Very little research has been done on the subject in children, but one study did find that younger children experience greater post-awakening disorientation than older children.

Children have a much greater need for sleep because of their rapid growth and development. Babies and young children take naps throughout the day to supplement their nighttime slumber. Some children nap for up to 3 hours or longer in the afternoon, so the opportunity for sleep inertia is higher. 

Most parents agree that kids are not in the greatest moods when they wake up. My children rarely wake up happy and smiling. As babies and toddlers, they often woke up crying and confused.

Symptoms of sleep inertia are likely worse in kids when they have to be woken up for school or some other activity versus when they are able to wake up naturally on their own. During the teenage years, SI increases because teens biologically have later circadian rhythms and are forced to wake up before their bodies are ready thanks to early school start times. 

In children, sleep inertia can also be a symptom of a type of parasomnia called “confusional arousal.” This disorder is most common in infants and toddlers and causes them to wake up crying and upset, often unable to console. Episodes can last up to 30 minutes, ending with children falling back asleep.

Check Out Our Guide: How Much Sleep Do Kids Need? and Beds for Teenagers

Questions for the Doctor

Do I have a disorder?

Sleep inertia isn’t a disorder, and it, in most cases, is normal. It is more likely to occur in individuals who are sleep deprived, either due to less opportunity for rest (like shift work or having a new baby) or because of an underlying sleep disorder. 

If you experience severe sleep inertia even after getting a good night’s rest and waking without an alarm, it may be a good idea to speak to your doctor about your symptoms.

How do I know if I’m getting enough sleep?

The “right” amount of sleep differs from person to person, but most adults need between 7-8 hours a night. One of the best ways to test how much sleep you need is to spend a few days going to bed at the same time and allowing your body to wake up naturally without an alarm. If you wake up at approximately the same time and feel well-rested upon awakening, then you’re probably getting enough sleep.

Could this be depression?

Depression and many other psychiatric disorders can impact sleep, including difficulty waking and getting out of bed. Many people with these conditions also feel excessively tired throughout the day. In some cases, SI could be a sign of depression or another psychiatric disorder so it’s important to discuss these concerns with your doctor if you feel this could be the case. 

Need more info? Find out more about the link between sleep and depression.

Is this normal in children?

Sleep inertia is normal in children, just like in adults. Younger children and teenagers are the most susceptible to symptoms based on changes in their circadian rhythms, but SI can occur at any age. 

If you notice that grogginess and confusion persist throughout the day, it could be a sign that something else is going on. Sleep disorders and other conditions like sleep apnea can also cause daytime fatigue, so it’s important to talk to your child’s pediatrician if you suspect something is wrong.

Is there a safe way to cure it?

Unfortunately, there is no “cure” for sleep inertia. Scientists have been researching various methods to decrease the effects, but they haven’t found any way to prevent it entirely. The good news is that the symptoms are short-lived in most people, and there are some strategies you can use to help it dissipate more quickly. 

How to Shorten the Duration

Blame it on genetics or your newborn infant who still isn’t sleeping through the night, but some people are just more likely to suffer from morning grogginess than others. If you’re one of the unfortunate souls who struggles to remember how to operate the toaster first thing in the morning, you may be disappointed to hear that there’s no magic cure for sleep inertia. But, there are some tips and tricks you can try to lessen its duration.

No Early Morning Rocket Science

The first 30 minutes after you wake up in the morning is not the time to be solving big problems like world peace (or even small ones like whether or not to respond to that controversial post on Facebook). Likewise, give yourself time to wake-up before driving or operating heavy machinery (kitchen appliances included).

Set Your Alarm at the Same Time Every Day

Going to bed and waking up at the same time every day trains your circadian rhythm (your body’s internal clock). As long as you give yourself a sufficient sleep window of 7-8 hours, you should notice that you feel less tired when you wake. Some people even find that they start waking just before their alarm or no longer need an alarm clock at all.

Use a Wake-up Light

Wake-up lights (a.k.a. sunrise-simulators) are a type of alarm clock that gradually increases the light in your bedroom, simulating the natural rise of the sun. Light therapy has been used to treat sleep disorders and one study found that gradually increasing light during the last 30 minutes of sleep improved alertness and cognitive and physical performance after waking.


View Our Guide: Best Light Therapy Lamp

Have a Morning Routine

Similar to a bedtime routine to help you sleep, having a morning routine that involves performing the same acts day after day could help to signal your body that it’s time to be awake. According to some research, morning meditation may be a good activity to incorporate into your routine because it improves focus and attention.

Wash Your Face

Splashing cold water on the face has been a popular method for self-awakening for centuries. While there isn’t a lot of evidence proving that it works, one study did show that napping followed by splashing water on the face helped to reduce feelings of sleepiness. Hey, even if it doesn’t work, at least you have a clean face!


A morning work-out may not be everyone’s cup of tea, but it has its merits. Exercise is a great way to get the blood flowing and shake off morning grogginess. Bonus points if it takes you outside where you also get some exposure to natural morning sunlight.

Caffeine (In Moderation!)

Several studies have reported the benefits of caffeine on reducing sleep inertia. The only problem is that it takes some time to kick in (usually 20-30 minutes to notice the full effect). It’s important to keep caffeine in moderation or it could interfere with your ability to fall asleep at night (making morning grogginess worse over time).

Read More: Caffeine and Sleep

Give Yourself Time to Wake Up

When all else fails, give it time. Most people notice that sleepiness clears within 30 minutes of waking, so plan accordingly and give yourself some extra time to wake up.


Super annoying? Yes. Life-threatening? No. Sleep inertia appears to be something most humans experience, some more severely than others.

Morning grogginess can put a damper on your morning, but it should clear within a half-hour of waking. So sip your coffee, meditate, and remember – no making major life decisions right after you wake up.

Having trouble of getting a good night sleep? Take a look at our list of best mattresses of 2024

Raina Cordell

Raina Cordell

RN, RHN, Certified Health Coach

About Author

Raina Cordell is a Registered Nurse, Registered Holistic Nutritionist, and Certified Health Coach, but her true passion in life is helping others live well through her website, Her holistic approach focuses on the whole person, honing the physical body and spiritual and emotional well-being.

Combination Sleeper