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

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! 

“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.

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:

• Obstructive sleep apnea
• Insomnia 
• Restless leg syndrome 
• Periodic limb movement disorder 
• Narcolepsy 
• Hypersomnia 
• Bruxism (or teeth grinding) 

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: 

• Antidepressants
• Antihistamines
• Birth control for some
• Sleep aids 
• Weight loss drugs like Ozempic and Wegovy  

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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.

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. 

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.