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Why Do I Wake Up Tired After 8 Hours of Sleep? A Sleep Doctor Explains

You’re probably waking up tired after eight hours of sleep because you need more sleep or better quality sleep, or you don’t have a regular sleep schedule.
Written by
Jeff Kahn, M.S., Rise Science Co-Founder
Reviewed by
Jamie Zeitzer, PhD, Rise Science Scientific Reviewer
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We bring sleep research out of the lab and into your life. Every post begins with peer-reviewed studies — not third-party sources — to make sure we only share advice that can be defended to a room full of sleep scientists.
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Updated Regularly
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Man waking up in the morning but still tired

Quick Summary 

  • You might be waking up tired after eight hours of sleep because you need more sleep than this, you aren’t getting good quality sleep, you’ve got some sleep to catch up on, or you have an irregular sleep schedule. 
  • Stress, anxiety, bad sleep habits, a sleep disorder, or a medical condition could also cause daytime sleepiness, even after eight hours of sleep.
  • The RISE app can tell you how much sleep you need, how much sleep you have to catch up on, and guide you through 20+ good sleep habits to help you get the most restorative sleep possible.

You’ve had eight hours of solid sleep. You should be jumping out of bed ready to take on the day, right? 

Well, that’s not always the case. Even after what seems like enough sleep, you might find yourself snoozing your alarm clock, feeling groggy all morning, and reaching for coffee just to get you through the afternoon. 

There are some likely culprits behind this tiredness and — luckily — they can be fixed. 

Below, we’ll explain why you’re waking up tired, how to stop waking up tired, and how the RISE app can make this easier. 

Reasons Why You’re Waking Up Tired After 8 Hours of Sleep

Here’s why you could be waking up tired — even after eight hours of sleep. 

1. Waking Up Groggy Is Normal 

Sleep inertia is the most common cause of morning tiredness. 

Sleep inertia is the groggy feeling you get when you first wake up. It can last from 15 minutes to about two hours, and it’s totally normal, even if you’ve had enough sleep. 

Dr. Jamie Zeitzer, co-director of the Center for Sleep and Circadian Sciences at Stanford University and one of our advisors, found sleep inertia doesn’t just cause daytime sleepiness — it lowers people’s mental performance during the first two hours after waking up.

Other symptoms of sleep inertia include disorientation and brain fog. 

Symptoms of sleep drunkenness, a more severe form of sleep inertia, include confusion, slowness, and lack of coordination. Sleep drunkenness can last up to four hours. 

Research is mixed on whether hitting the snooze button prolongs sleep inertia or reduces its duration. However, it’s more certain that setting multiple alarms before your final wake-up time can reduce how much restorative sleep you're getting and lead to waking up feeling tired.

You can check RISE for a prediction of how long your grogginess will last each morning.

We’ve covered how to get rid of sleep inertia here. 

2. You Need More Than 8 Hours of Sleep 

Despite what you might hear, we don’t all need eight hours of sleep. How much sleep you need is based on genetics and unique to you. So, if you’re waking up tired after eight hours, you may need more sleep. 

We looked at how much sleep 1.95 million RISE users aged 24 and up needed and found 48% needed eight hours or more sleep. Some needed up to 11 hours 30 minutes! 

The RISE app can tell you how much sleep you need
How much sleep RISE users need.

“If you’re getting eight hours of sleep and still feeling tired each day, you may need more rest than that,” says Dr. Chester Wu, Rise Science sleep advisor, medical reviewer, and double board-certified doctor in psychiatry and sleep medicine. 

“Eight hours is a good starting point, but we all need a different amount of sleep. Try heading to bed a little earlier than usual and seeing how you feel.”

3. You’re Getting Less Sleep Than You Think  

If you’re feeling sleepy, you might not actually be getting eight hours of sleep. 

Many of us forget about sleep efficiency — this is the amount of time you spend sleeping while in bed. It takes into account the time it takes you to fall asleep and any time you’re awake during the night.  

Even with sleep efficiency in mind, working out how much shut-eye you get is no easy feat. 

Sleep studies show self-reported sleep data is often inaccurate, and even wearable devices can get it wrong. Sleep trackers can confuse pre-bed screen time for sleep, for example, so you may get an inflated number. 

All this is to say, you might be spending the right amount of time in bed, but not enough time actually sleeping.  

4. You Need to Catch Up on Sleep 

If you need eight hours of sleep a night, but you’ve only been getting six hours lately, you may feel tired, even after a full night’s sleep. This is because you still have some sleep to catch up on. 

To find out, check RISE to see if you have any sleep debt. This is the amount of sleep you owe your body. The more sleep debt you have, the more tired you might feel each morning. 

Sleep debt can make sleep inertia and daytime sleepiness feel worse.

You may also temporarily need more sleep if you’re recovering from illness or intense exercise.

RISE app screenshot showing how much sleep debt you have
RISE can tell you how much sleep debt you have.

5. You Have an Irregular Sleep Schedule  

An irregular sleep schedule can disrupt your circadian rhythm (your body clock), leaving you low on energy, even if you’re getting enough sleep at irregular times. 

One sleep study looked at two groups who got the same amount of sleep, but one group got this sleep on a regular schedule. The group with regular sleep patterns felt more energy and alertness. 

When your sleep patterns are all over the place, your alarm is more likely to ring during deep sleep, making you wake up feeling tired. 

Having an irregular sleep schedule also means your cortisol levels are high and low at the wrong times. You want higher cortisol in the morning to feel alert and lower in the evening to fall asleep. Lower morning cortisol could make it feel like you've not yet woken up. 

And while an irregular sleep schedule may be unavoidable with shift work, even sleeping in on weekends can cause you to wake up feeling tired. This is known as recovery sleep, and research shows it can make sleep inertia worse, even though catching up on sleep is beneficial.

RISE can tell you the best time to go to bed and wake up each day based on your circadian rhythm. Try sticking to these sleep times to reduce morning grogginess and daytime sleepiness. 

6. You’re Stressed or Anxious 

Stress or anxiety can keep you up at night or cause restless sleep, making you feel tired the next morning — and all day. 

Stress or anxiety can also make you feel mentally exhausted, even after eight hours of sleep, adding to your grogginess.

RISE users say stress and anxiety are their biggest challenges for getting a good night's sleep and waking up refreshed. 

7. You Have Bad Sleep Habits

Bad sleep habits — known as poor sleep hygiene — can make it harder to fall asleep and stay asleep through the night. So, you’re more likely to not get enough sleep. 

Even if you are getting enough sleep overall, your sleep may be broken and poor quality, which isn’t as restorative as non-broken sleep. 

Plus, poor sleep hygiene makes it harder to get enough of each sleep stage, like deep sleep and REM sleep. 

Bad sleep hygiene includes:  

  • Not getting natural light exposure in the morning
  • Getting too much blue light in the evening 
  • Letting too much screen time before sleep push back your bedtime 
  • Eating an unhealthy diet, including one high in sugar or ultra-processed foods
  • Drinking coffee and alcohol and eating large meals too close to bedtime 
  • Not getting enough exercise or doing intense exercise too close to bedtime 
  • Drinking too much water before bed, causing middle-of-the-night bathroom trips 
  • Your bedroom being too hot, humid, bright, or noisy  

Lifestyle factors like dehydration, being too sedentary, and not getting enough bright natural light during the day can also cause daytime fatigue and impact your sleep quality.  

RISE can help you maintain good sleep hygiene. More on that soon. 

8. You Have a Sleep Disorder 

A sleep disorder can make it hard to get the sleep you need at night, leaving you with morning and daytime sleepiness. 

Sleep disorders that can cause you to wake up tired include:

A snoring bed partner or a co-sleeper with a sleep disorder can also cause you to wake up tired. 

9. You Have a Medical Condition 

An underlying medical condition could be the reason you’re waking up tired

These include: 

  • Hypothyroidism (underactive thyroid) 
  • Iron deficiency anemia
  • Nutrient deficiencies in magnesium or B vitamins
  • Mental health issues like depression and anxiety  
  • Heart disease 
  • Chronic fatigue 
  • Diabetes 

You might also be waking up tired because your period, pregnancy, or menopause is messing with your sleep, and therefore your next-day energy levels. 

And some medications come with tiredness as a potential side effect including: 

We’ve covered more on why you’re always tired here, including why it’s normal to feel tired in the afternoon. 

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How Much Sleep Do I Need? 

One common reason you’re still sleepy after eight hours of sleep is because you need more than eight hours. 

General guidelines say adults should get seven to nine hours of sleep, but these guidelines are based on how much sleep people get, not how much they need. How much sleep you need is genetic and unique to you.

How do you know how much you need?

You can try waking up without an alarm for two weeks and keeping track of your sleep times, noting when they start to regularize (known as the sleep rebound method). But this is often inaccurate — not to mention most of us don’t have the luxury of waking up without an alarm.

The more accurate (and quicker!) way of finding out how much sleep you need is to use the RISE app. 

RISE uses a year’s worth of your phone behavior and sleep science algorithms to work out how much sleep you need

RISE also works out your sleep debt, so you know if your body wants to temporarily sleep for longer to play catch up.

RISE app screenshot showing your sleep need so you can keep sleep debt low
RISE tells you how much sleep you need.

How to Stop Waking Up Tired 

Now you know why you’re most likely feeling tired after eight hours of sleep, it’s time to fix it. 

Here’s how you can stop waking up tired: 

  • Get enough sleep: Use RISE to work out how much sleep you need and start aiming for that each night. Add a buffer of 30 minutes to an hour to account for any time awake in bed. This will help reduce tiredness each morning and all through the day.
  • Catch up on sleep: Take a nap, head to bed a little earlier tonight, or sleep in a little later tomorrow. Aim to keep your sleep debt below five hours to maximize your energy levels. We’ve covered more tips on catching up on sleep here.
  • Keep a regular sleep schedule: Go to bed and wake up at the same times each day, even on weekends. A regular sleep pattern like this can help you get enough sleep and boost your energy levels. 
  • Improve your sleep habits: RISE can walk you through 20+ good sleep habits, such as when to get and avoid blue light and when to avoid caffeine, large meals, intense exercise, and alcohol. RISE can also remind you to check your sleep environment before bed. This will help you fall asleep, stay asleep, and get better quality sleep — and enough of it — each night.
  • Reduce stress and anxiety: Try winding down before bed by reading, taking a warm shower or bath, or doing some breathing exercises. Check out RISE’s guided relaxation exercises to get started. 
  • Improve your morning routine: Resisting the snooze button, playing your favorite music, doing some exercise, drinking some coffee, and eating a breakfast rich in complex carbohydrates — like oatmeal, whole-wheat bread, and fruit — can help you shake off tiredness to feel more awake each morning. 
  • See a doctor: If you’re still feeling tired each morning or falling asleep during the day, speak to a doctor to find out if a sleep disorder or health issue is to blame. 

Need a quick pick-me-up? We’ve covered ways to wake yourself up here. 

RISE app screenshot showing sleep hygiene habit reminders
RISE can help you improve your sleep hygiene.

You Can Stop Waking Up Feeling Tired

RISE can work out how much sleep you need, how much sleep debt you have, predict the timing of your circadian rhythm, and guide you through 20+ good sleep hygiene habits each day.

All this can help you get enough sleep and more energy. And it can happen sooner than you think — 80% of RISE users feel the benefits within five days. 

“Just being able to visually see how my sleep habit choices are affecting my energy levels, seems to have done the ticket for getting me to catch up on sleep.” Read the review.


Waking Up Tired After 8 Hours of Sleep FAQs

Why am I still tired after 8 hours of sleep?

Feeling tired after eight hours of sleep might be because you need more sleep or you have an irregular sleep schedule. A disruptive sleep environment, certain dietary and lifestyle choices, having a sleep disorder or medical condition like anemia or an underactive thyroid can also impact the quality of your sleep. Consult a sleep specialist for more tailored advice.

Why am I still tired after a full night of sleep?

You might be tired after a full night of sleep because you’re sleep deprived from previous nights, you’re stressed, you have an irregular sleep schedule, a sleep disorder like insomnia or restless leg syndrome, or poor sleep habits causing bad sleep quality. Talk with your doctor to help you identify the root cause and the best solutions for you.

Should I go back to sleep if I wake up tired?

The occasional snooze may help you catch up on sleep, but generally, you shouldn’t go back to sleep if you wake up tired. Instead, address the underlying cause. Waking up groggy is normal even if you’ve had enough sleep, but if you frequently wake up feeling tired and experience excessive tiredness all day, catch up on sleep, and optimize your sleep hygiene, bedtime routine, and sleep environment for better sleep quality. A sleep specialist can also help you identify longer-term solutions.

How can I stop waking up tired?

To stop waking up tired, address the possible causes. Catch up on sleep, keep a regular sleep schedule, create an optimal sleep environment, and manage stress before bed. Evaluate your diet, lifestyle, and medications for anything that might impact your sleep quality. If you suspect a sleep disorder, seek a sleep specialist for advice.

Why don’t I feel rested after sleeping?

You may not feel rested after sleeping because you haven’t had enough sleep or you have an irregular sleep schedule. Disruptions in your sleep stages, particularly if you don't get enough deep sleep, can affect how rested you feel. Stress, sleep disorders, or health conditions like anemia or thyroid issues can also contribute by impacting your sleep quality. Assess and adjust your sleep routine and environment, and consult your doctor if you consistently wake up feeling tired.

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Rise is the only app that unlocks the real-world benefits of better sleep.

Instead of just promising a better night, we use 100 years of sleep science to help you pay down sleep debt and take advantage of your circadian rhythm to be your best.

Over the past decade, we've helped professional athletes, startups, and Fortune 500s improve their sleep to measurably win more in the real-world scenarios that matter most.

Rise Science is backed by True Ventures, Freestyle Capital, and High Alpha; investors behind category winners Fitbit, Peloton, and Salesforce Marketing Cloud.

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