Your Guide to Sleep Inertia

Written by
The Manual Team
Medically approved by
Dr Earim Chaudry
Last updated
1st February 2022

In 30 seconds

Sleep inertia is the feeling of grogginess, drowsiness, or disorientation you feel immediately after you wake up. For most people, it disappears quite quickly as you transition to wakefulness. For others, it can last a lot longer. If you struggle with prolonged sleep inertia, there are things you can do to make things easier. Drinking caffeine right after waking up, exposing yourself to natural light, and fixing your sleep schedule in general will help.

When You Just Can’t Seem to Wake Up

There are as many types of sleep problems as there are people who struggle with sleep. While many people struggle to fall asleep and others wake up during the night, there are also those who have difficulties waking up in the morning.

If that’s you, you’re struggling with sleep inertia.

Feelings of grogginess immediately after you wake up are normal. But if you can’t seem to shake off these feelings, it may signal a deeper problem with your sleep.

Here, we’re sharing everything you need to know about sleep inertia – from what causes it to what you can do to feel fresher in the morning.

What is Sleep Inertia?

Sleep inertia – sometimes known as sleep drunkenness – refers to the feelings of disorientation, sleepiness, and cognitive impairment that you feel when you wake up. It’s that morning grogginess or mild confusion that hangs over you before you’re fully alert and awake.

The symptoms of sleep inertia are probably familiar to most of us:

  • Grogginess
  • A desire to go back to sleep or hit the snooze button
  • Impaired cognitive ability
  • Impaired spatial awareness (you may be clumsy or disorientated)
  • Impaired attention (you might not notice things that you otherwise would)
  • Low mood.

Usually, these feelings only last between 15 minutes and an hour. However, in some people on certain days, they can last much longer – and there can be days when you never really feel like you have fully woken up at all. In this case, doctors refer to a condition known as prolonged sleep inertia.

This can become a problem. Sleep inertia can affect your reaction times, your decision-making capabilities, and your cognitive performance more generally. And if it lasts too long, it can affect how you perform at work or in other parts of your life.

But what causes sleep inertia?

The Causes of Sleep Inertia

The exact cause of sleep inertia is still unknown. But scientists are exploring three main possibilities:

  • Reduced blood flow. Blood flow to the brain depends on the stage in your sleep cycle. For example, in deep sleep, cerebral blood flow appears to be slower than in other stages of sleep. If you have an abrupt awakening in the middle of deep sleep, blood flow to your brain may still be reduced, affecting your cognitive functions.
  • Delta waves. Delta waves are long, slow brain waves that are characteristic of non-REM sleep (or deep sleep). Studies suggest that people with severe sleep inertia have more delta waves on waking, while also having fewer beta waves (those waves typically associated with wakefulness). In this way, sleep inertia appears to happen when your brain is still showing the behaviours of deep sleep even after waking.
  • Adenosine. A chemical in the brain that helps us become drowsy, adenosine levels should be low when we wake up. Studies suggest that in sleep inertia, these levels are higher than normal.

But not everyone experiences sleep inertia in the same way. It is believed to be more severe in people who drink excessive alcohol, who suffer from other sleep disorders, or who do shift work. That’s because their normal sleep patterns are affected.

While sleep inertia can be difficult to manage, there are ways to feel better when your alarm clock rings. The following countermeasures have been proven to help you reduce the effects of sleep inertia:

Managing Sleep Inertia: Some Tips

  • Drink caffeine. It probably seems quite obvious – and it may be something that you have tried already – but there is strong scientific evidence to support the idea that drinking caffeine in the morning reduces the effects of morning sleep inertia. 

(Remember though: to get a good night’s sleep tomorrow, make sure you don’t drink caffeine 6 hours before going to bed.)

  • Light exposure. Exposing yourself to natural light in the early morning can help sleep inertia. That’s because it helps your body reset its circadian rhythm, the sleep-wake cycle. 
  • A short nap. Napping can help reduce the symptoms of prolonged sleep inertia – but only if you do it at the right time. A nap of 10 to 20 minutes appears to have the best effect.
  • Washing your face. Splashing cold water onto your face has been found to help cognitive impairment associated with sleep inertia.
  • Improve your sleep. Perhaps the most effective way to reduce the symptoms of sleep inertia is to improve your sleep overall. While this might not always be possible for some of us (such as night shift workers), there are always ways to improve our sleep. Let’s take a look at some of them:

Tips to Improve Your Sleep

Improving your sleep can help to reduce the effects of sleep inertia. Try these tips to get a good night’s sleep:

  • Aim for 7-9 hours of sleep. Feeling fresh in the morning starts with getting enough sleep. Sleeping for the recommended 7 to 9 hours will reduce any symptoms of sleep deprivation.
  • Create a healthy sleep environment. Try to make the place in which you sleep as conducive to quality sleep as possible. It’s best if it is cool, quiet, dark, and calm.
  • Cut down on alcohol. Alcohol helps you get to sleep but reduces sleep quality overall – and that won’t improve your morning mood.
  • Skip caffeine late in the day. Caffeine can wake you up in the morning, but it will affect how well you sleep if you drink it before bed. Even drinking caffeine 6 hours before sleep can reduce your sleep quality.
  • Exercise. Physical activity is part of a healthy lifestyle – and it has been found to make restful sleep easier to achieve. Try to do at least 150 minutes (5 sessions of half an hour) of physical activity a week.
  • Stick to a bedtime routine. Have a relaxing bath, practise meditation or mindfulness, or take a sleep supplement. Going to bed and waking up at the same time each day will help too.

Key Takeaways

Sleep inertia can be frustrating and debilitating if it happens often or lasts for a long time. But there are effective ways to manage it. Caffeine should reduce the effects of sleep inertia in the short term, while creating a healthy sleep routine will be a longer term solution.

At Manual, we can help you get a good night’s sleep. Find the best option for you.


How Do I Know If I Have Sleep Inertia?

You have sleep inertia if you feel groggy, disorientated, or generally below your best when you wake up. It doesn’t have to happen every day. If it lasts for over an hour, you may have prolonged sleep inertia – a more severe form caused by changing sleep patterns, shift work, or sleep deprivation.

What is Fatigue Inertia?

Fatigue inertia is another name for sleep inertia, the feeling of grogginess and disorientation when you wake up.

How Long Does Sleep Inertia Last?

In generally healthy people, sleep inertia typically lasts about 15 minutes to half an hour. However, you may not be completely at your best before 2 hours after waking.

If you are experiencing sleep inertia for longer than this, you may have it quite severely. Improving the quality of your sleep can help.

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

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