Everything You Need To Know About Sleep Inertia

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experiencing sleep inertia

Ever wonder why you don’t (or can’t) just spring out of bed ready to rock ‘n’ roll and move mountains when your alarm goes off every morning? Well, we’re all off to a slow start in the AM courtesy of a little thing known as sleep inertia. Instead of feeling like you’re flipping a switch every morning, sleep inertia turns waking up into a multi-step process. 

What Is Sleep Inertia? 

According to Dr. Chelsie Rohrscheib, head sleep expert and sleep scientist at Wesper, “Sleep inertia is a state of extreme grogginess and cognitive dysfunction immediately after waking that is often accompanied by symptoms such as excessive drowsiness, confusion, brain fog, nausea, and headache.” 

“Most people will experience sleep inertia at some point in their life, but some experience it more frequently or even daily,” she says. While its duration varies from person to person, sleep inertia can last anywhere from a few minutes to an hour. Sleep inertia can occur just as easily after a full night’s sleep as after a long midday nap. Men and women experience sleep inertia equally, and while kids and adolescents frequently experience confusion with sleep inertia, confusion becomes less of an issue with age. 

What Causes Sleep Inertia?

“People who are chronically sleep-deprived or undercut their nightly sleep time are at higher risk for sleep inertia,” says Rohrscheib. Beyond short sleep and sleep deprivation, she adds, “Certain sleep disorders, such as sleep apnea, can also increase a person’s risk. Likewise, “individuals that rely heavily on an alarm to wake them up compared to those that wake up naturally, or wake up before their alarm, are also more likely to suffer from bouts of sleep inertia.” 

Digging a little deeper, we find some research that suggests sleep inertia may be a result of waking before the adenosine (a neurotransmitter in our brain that encourages our sleep drive) is fully cleared out of our system or the result of an increase in delta waves (the high-amplitude brain waves that are associated with deep sleep) in the posterior regions of the brain, which causes a slower reactivation of these areas after waking.

The Four Sleep Stages

NREM Stage 1

  • Transition phase between wakefulness and sleep
  • Lightest sleep stage 
  • Heartbeat, breathing, and brain activity begin to slow 
  • Large muscles relax

NREM Stage 2  

  • Medium sleep 
  • Accounts for about 50 percent of total sleep time
  • Individual begins to disengage from their environment
  • Breathing and heart rate continue to slow
  • Body temperature begins to drop

NREM Stage 3 

  • The deepest stage of sleep (also known as slow-wave sleep or delta sleep) 
  • Delta waves emerge 
  • Muscles are completely relaxed, blood pressure drops, and breathing decreases further
  • The sleep stage most commonly associated with growth, repair, and sleep inertia 

REM Stage 4 

  • The stage where emotions and memories are processed and stored
  • Sleep stage where most dreaming occurs
  • Brain activity closely resembles its activity during waking hours
  • Breathing is irregular and fast
  • Limbs are temporarily paralyzed

“Scientists believe sleep inertia occurs when we wake during the wrong stage of sleep,” says Rohrscheib. “Most people wake up during either light sleep or REM sleep, when the brain is still in a high-activity sleep,” she continues. “Individuals who frequently experience sleep inertia may be inappropriately waking during deep sleep (stage 3) when brain activity is very quiet and slow. The brain is not very good at transitioning quickly from deep sleep to awake, and it can take some time for the brain to ‘come back online,’ which results in the symptoms of sleep inertia.” 

Research also shows that chronotype can affect your experience of sleep inertia. Not only do night owls or wolf chronotypes report more instances of sleep inertia, but research also shows that the cognitive impairments and symptoms of sleep inertia tend to last longer for this chronotype. Shift work can also exacerbate sleep inertia

Symptoms of Sleep Inertia 

There are many levels to sleep inertia, and everyone’s experience may be different. Typically, the most common symptoms of sleep inertia include:

How to Get Diagnosed for Sleep Inertia

“Sleep inertia is common but not normal, especially if you experience sleep inertia frequently,” says Rohrscheib. “Having an odd bout of sleep inertia every once in a while is not a cause for concern. If you are experiencing sleep inertia frequently, such as a couple of times per week, consider speaking to your doctor.” 

To expedite the process, consider keeping a sleep diary for a week or two prior to your appointment. A sleep diary can help your doctor make a more accurate diagnosis or generally determine the next steps. If there is any suspicion of a sleep disorder, ask your doctor about having a sleep study. 

Managing Sleep Inertia 

Maintaining good sleep hygiene habits will improve your overall sleep quality and help maximize the sleep you’re getting. 

Grab a Cup of Joe

While most resources on sleep will warn you against consuming caffeine, sleep inertia may be the one exception. In this case, your morning cup of joe is more helpful than harmful. Essentially, caffeine does the heavy lifting to block adenosine receptors in your brain, and after that first cup, you’re likely to feel more awake and alert. Cheers to that. 

Practice a Little Light Discipline

Be sure to maintain proper light discipline throughout the day to keep your circadian rhythm in check. This means exposing yourself to light early in the day and reducing that exposure as bedtime approaches. If need be, try blackout curtains in your room or an eye mask

Check the Thermostat

Sleeping in a room that’s too warm can impede your ability to get some shut-eye and further exacerbate the effects of sleep inertia come morning. To ensure you’re getting enough sleep, try adjusting the thermostat in your sleeping environment. The ideal temperature for sleep is somewhere between 65 to 67 degrees, though this may vary slightly depending on the heat-retaining (or cooling) properties of your pajamas and bedding. 

Tame Your Alarm Clock

Alarm clocks are notorious for loud, obnoxious noises that rip us from our sleep. This can be incredibly irritating and exacerbate the confusion and grogginess associated with sleep inertia. For a more gentle wake-up, consider setting the alarm on your smartwatch that’ll wake you with gentle vibrating taps, or invest in a sunrise alarm clock that simulates a gradual sunrise to wake you more naturally. 

Take a Nap

Take naps during the day if you need to, but be sure to keep it under 30 minutes. Long afternoon naps can reduce your sleep drive come bedtime, ultimately disrupting your circadian rhythm and worsening sleep inertia. 

Make Sure You’re Getting Enough Sleep 

“Getting enough sleep at night will reduce the likelihood of waking up during deep sleep, which primarily occurs in the first half of the night,” says Rohrscheib. “If you’ve had enough sleep, the end of your night should be dominated by REM and light sleep, which is more appropriate for waking.” 

Lean into Your Chronotype

“Make sure that the time you are sleeping is appropriate for your internal biological clock, or your circadian rhythm,” says Rohrscheib. “If you are trying to wake up much earlier or much later than your biological clock dictates, this can lead to more episodes of sleep inertia.” 

The Last Word From Sleepopolis 

Sleep inertia is the transitional state between sleep and wake. Most people will experience it at some point in their life, and while it presents differently from person to person, the most common symptoms are sleepiness, grogginess, and impaired cognition. 

Sleep inertia may be frustrating, but it’s generally not dangerous save for some professions like military personnel and healthcare workers, who often need to make cognitively sharp decisions at the drop of a hat. Managing your sleep hygiene, timing your daily light exposure, and enjoying your morning coffee are some of the more common ways to manage sleep inertia. 

Sharon Brandwein

Sharon Brandwein

Sharon Brandwein is a Certified Sleep Science Coach and a freelance writer. She specializes in health and beauty, parenting, and of course, all things sleep. Sharon’s work has also appeared on ABC News, USAToday, and Forbes. When she’s not busy writing, you might find her somewhere curating a wardrobe for her puppy.