Wondering Why You're Tired After 8 Hours Of Sleep? Here's Why — Plus What To Do.

Most of us are no strangers to not getting enough sleep. When your schedule gets busy, sleep is often the part of our routine that falls to the wayside. But let’s say it doesn’t — you get to sleep early and wake up a blissful eight hours later. What if all that sleep doesn’t seem to work as advertised? If you’ve been diligent to get the recommended amount of sleep and still drag all day, you may ask, “Why am I tired after 8 hours of sleep?” Read on to find out what may be keeping you up at night.

Note: The content on Sleepopolis is meant to be informative in nature, but it shouldn’t be taken as medical advice, and it shouldn’t take the place of medical advice and supervision from a trained professional. If you feel you may be suffering from any sleep disorder or medical condition, please see your healthcare provider immediately.

Long Story Short

Most adults need seven to eight hours of sleep per night. You can discover how much you need by using the sleep rebound method, keeping a sleep diary, and trying out a few sleep calculators.
You may still be tired after eight hours of sleep because of sleep debt, jet lag, medical conditions, or poor sleep quality.
Get better sleep using sleep hygiene techniques and stay more alert during the day by getting out in the sun, exercising, and adjusting your diet.

Your Body May Need More Than 8 Hours Of Sleep

How are you supposed to know how much sleep you need, exactly? Though sleep needs may vary, experts generally recommend tackling sleep goals by following age-specific guidelines: (1)

0–3 months: 14–17 hours per 24 hours (including naps)
4–12 months: 12–16 hours per 24 hours (including naps)
1–2 years: 11–14 hours per 24 hours (including naps)
3–5 years: 10–13 hours per 24 hours (including naps)
6–12 years: 9–12 hours per 24 hours
13–18 years: 8–10 hours per 24 hours
18–60 years: 7 or more hours per night
61–64 years: 7–9 hours per night
65 years and older: 7–8 hours per night

But what if these recommendations don’t seem to work for you? We know that a lucky few people have the “short sleeper” gene, which lets them feel rested after only four to six hours. (2) (How is that fair?) If some people can get by with less sleep, do others need more?

The short answer is yes — sleep isn’t a one size fits all model. “Determining the exact amount of sleep an individual needs can be a nuanced process,” says Dr. Chester Wu, MD, sleep medicine physician in Houston, TX. He adds that “feeling alert” can be deceiving because we can adapt to chronic sleep deprivation and may not feel tired. So how do you figure out how much sleep you actually need? Read on!

Step One: Sleep Rebound Method

The ”sleep rebound method” can help you figure out how much sleep you need, Wu says. First, you have to pay off your sleep debt (more on this later). Then you go to bed at your normal time but turn off your alarm, allowing yourself to wake up naturally. After a minimum of one week, you’ll get an idea of how much sleep your body wants each night.

This method, sometimes called a “sleep vacation” may sound impossible with work, children, and other responsibilities. The best time to try it is on a week off of work or on vacation, says Wu.

Step Two: Keep a Sleep Diary

Write down when you go to bed, when you wake up, how you feel upon waking, and any times you remember waking up through the night (just wait till morning to do this!). You can also ask your bed partner about any snoring or movement they remember from the night. This information can help you find out not only how much you’re sleeping, but how well. (3) It’s key to try to do this daily, too—if you sit down with your sleep diary on Friday and try to remember how you slept on Tuesday night, you likely won’t have the most accurate results.

Or… Try a Sleep Calculator

You can find handy sleep calculators all over the internet. Sleepopolis’ sleep calculator helps you figure out your ideal bedtime and tells you how many sleep cycles you can expect.

As an adult, if you need more than eight or nine hours of sleep regularly, it’s not a bad idea to check with your primary healthcare provider to rule out sleep disorders or medical conditions that could play a part in your sleepiness.

You Have Sleep Debt

Missing sleep is like borrowing from a bank — you’re going to have to pay it back eventually. Most people catch up on their “sleep debt” over the weekend, but you may still feel tired during the weekdays. (4)

Sleep Debt, Explained

Say, for example, you only get six hours of sleep each weekday, but your body needs eight. Each weeknight, you rack up two hours of sleep debt, so by the time the weekend comes, you have ten hours of sleep to catch up on. If you sneak in an eight-hour night of sleep mid-week, you may still feel tired because of sleep debt.

You can try to make up for lost sleep with daytime naps, but these don’t give you the same quality of rest as nighttime sleep. (5) If you are feeling tired during the day, you may have some sleep debt to pay down. (4) Check out our sleep debt calculator to see how much extra snoozing you need to catch up.

Jet Lag

Airplane travel lets us visit most places in the world within just a day or two. As fun as travel can be, moving across three or more time zones can confuse your circadian rhythm, or internal clock, and give you jet lag. Your circadian rhythm tells your body when it’s time to get sleepy and time to wake up. (6)

When you travel across time zones, you jump into a different part of the day than your departure city. So, as the sun begins to set, your circadian rhythm says, “Wait a minute! It’s too soon for bed!” You may find yourself waking up at 2 a.m. or unable to keep your eyes open at 2 p.m.

Jet lag can last one to three days, depending on how fast you adjust. (7) Try our jet lag calculator to shorten that time or maybe even skip it altogether! Seeking exposure to natural light, incorporating physical activity into your travel routine or trying out a natural sleep aid* may help speed up the process. (6)

You Didn’t Sleep As Much As You Thought

If you get in bed at 10 p.m., fall asleep quickly, and wake up at 6 a.m., you may feel confused as to why you still feel tired. Sometimes, though, we may sleep poorly without being aware of it.

Waking up eight hours after you went to sleep doesn’t mean you slept for that full amount of time — poor sleep hygiene and stress can make “enough” sleep feel insufficient. (8) “Fragmented sleep, in particular, can feel particularly fatiguing even if added all up, it amounts to someone’s sleep need,” Wu says.

You may also feel tired because you didn’t spend enough time in deep sleep, says Wu. It may sound strange to think you’re sleeping and not getting enough rest, but hear us out: When you spend too much of the night in light sleep, it can feel like you slept enough, but your body hasn’t gotten to reap the restorative benefits of deep sleep, so you still feel tired. (9)

Deep Sleep vs. Light Sleep

For adults, light sleep (stage N1) only lasts one to five minutes, and it happens before your body has completely relaxed. In your deepest stage of sleep (stage N3/slow wave), your body repairs damage, builds tissue, and strengthens your immune system. (10)

Medical Conditions That May Make You Tired

Even if you “do everything right” when it comes to sleep, sometimes medical conditions can still disrupt your slumber. “Low blood counts, thyroid problems, chronic heart disease, chronic lung disease, chronic pain… all of those can cause tiredness during the day,” says Dr. Audrey Wells, MD, sleep and obesity medicine physician.

Sleep Disorders

Sleep disorders can make it tough to fall asleep or stay asleep. (11) Some, like sleep apnea or restless legs syndrome, can disrupt sleep without waking you up, says Wu.

Some common sleep disorders include: (11)

Insomnia: The most common sleep disorder, insomnia makes it hard to fall asleep and stay asleep.
Sleep apnea: This sleep disorder causes pauses in breathing during sleep that may last up to 10 seconds or more.
Restless leg syndrome (RLS): RLS causes uncomfortable pulling or prickling feelings in your legs that can only be fixed by moving them.
Circadian rhythm disorders: These disorders mess with your internal clock and prompt wakefulness and sleepiness at the wrong times.
Parasomnia: These unusual behaviors during sleep can include walking, talking, or eating.

Mental Health Problems

Americans are dealing with mental health issues more than ever, with one out of every five adults reporting that they experience mental illness each year — and the effects of those mental health issues can bleed into nighttime. (12) Mental health issues like depression, anxiety, and stress commonly lead to sleep problems or fatigue. (12) (14) For example, 95 percent of people with major depressive disorder experience fatigue, and 50 percent of people with anxiety struggle with sleep, which can lead to fatigue. (15) (16)

Anxiety and depression can make sleep difficult, but problems sleeping can also cause flare ups with your mental health symptoms — so if you can, consider bolstering your sleep routine (more on that below). (17) (18)

If you’re feeling worried or discouraged about your mental health, please know that you are not alone, or without resources. You can reach out to any one of these organizations to get help and support:

Menstruation, Pregnancy, or Menopause

If you’ve had a period or two, you may already know it can come hand in hand with tiredness. (19) Hormonal changes during your menstrual cycle can also impact your circadian rhythm and throw off your usual sleep schedule. (20)

Pregnancy comes with its own kind of tiredness — growing another human is exhausting work, after all! Fatigue can crop up in any stage of the process, and what’s more, sleep can be elusive during pregnancy. (21) Frequent trips to the bathroom, increased heart rate, baby’s movements, and heartburn can all steal sleep every night. It’s no surprise these things can make you feel sleepy during the day. (22)

Unfortunately, sleep problems don’t end with periods and pregnancy. Menopause (the phasing-out of menstrual cycles) can also make you extra tired. (23) One small study surveyed 220 women in Taiwan and found almost 3 out of 4 menopausal women reported fatigue, which was much higher than pre- or perimenopausal reports. (24) Menopausal symptoms like hot flashes can also make it difficult to sleep, which predictably increases fatigue during the day. (25)

Heart Disease

When your heart is having trouble keeping up, you may feel extra tired. People with heart issues like coronary artery disease (CAD) and congestive heart failure (CHF) often report feeling fatigued. (26) The reason behind the connection is complex and includes other factors like how hard your heart is working, any mental health issues, and how you’re sleeping. (27)

When you have CHF, you can have a hard time breathing, which makes it tough to drift off. This shortness of breath can get worse when you lie down, which doesn’t help, either. (28) Between your provider’s treatment and some creative sleep positioning, though, you may still find a way to get some good snoozing in.

Hypothyroidism

We all have a small gland in our necks called the thyroid — this little guy releases a hormone that tells your body how to use energy. When you don’t make enough of this hormone (hypothyroidism), just about every body process can slow down, making you feel tired. But don’t despair – if you have hypothyroidism, you can take a medication that replaces the hormone you’re missing. (29)

Tips for Sleeping Better

When you’re extra tired during the day for more than a week and can’t explain why, a helpful first step is to visit your primary care provider. (30) They can rule out any sleep disorder or medical conditions listed above. Once those are crossed off, you can focus on these sleep hygiene tips and tricks for a better night’s sleep. (31)

Keep a regular sleep schedule: Try to go to bed and wake up at the same time.
Make your bedroom an oasis: Create a relaxing and cozy sleep space by shutting out light, keeping it cool and quiet, and investing in some comfortable bedding if you have the opportunity to do so.
Banish electronic distractions: Avoid blue light before bed and try to keep electronic devices out of the bedroom.
Time your snacks: Avoid caffeine, alcohol, and large meals up to three hours before you head to bed, says Wells.
Get active: If you can get in some physical activity during the day, you will fall asleep more easily at night.

“If you’re still sleepy,” says Wells, “you can try extending your sleep time a bit or changing the window in which you sleep, making that a little bit later or earlier.”

Tips for Feeling More Awake

The best way to feel more awake is to get plenty of quality sleep. (1) But while you’re figuring out how to do that or for the odd sleepless night, you can try these tips to stay alert during the day.

Get Some Sun

As soon as the sun peeks up, open the blinds and let that light pour in. “Exposure to natural light, especially in the morning, helps regulate the body’s internal clock and can boost alertness,” says Wu.

Move Your Body

We’re not trying to sound like a broken record here, but it’s true: Regular physical activity can not only give your energy levels a boost, it can help you sleep better, says Wu. “Research shows as little as 30 seconds of exercise can provide a sustaining boost of energy.”

Watch Your Diet

“Eating balanced meals and staying hydrated can prevent energy dips throughout the day,” says Wu. Try to eat just until you’re full, which can prevent post-meal grogginess. (32)

Also aim to stick with consistent snack and mealtimes, says Wells, who recommends avoiding highly processed foods for peak energy.

A Little Caffeine Is Okay

Many people reach for the coffee pot or a can of soda when they need a quick and easy lift. “Caffeine can temporarily increase alertness but effects wear off, so use it strategically,” Wu says. And be sure not to drink it too close to bedtime if you’re aiming for a good night’s sleep! Caffeine can stay in your system up to ten hours, so keep that in mind when you decide when to cut yourself off for the day. (33)

FAQs

Why am I still tired after drinking coffee?

The caffeine in coffee can offer a pleasing mental zing, but what happens when it’s not working? (34) When you drink too much caffeine over a long period, its effects can dwindle. (35) If you drink your coffee first thing in the morning, you may feel very sleepy until it starts to work, says Dr. Wu. Typically, caffeine starts to kick in 45 to 60 minutes after drinking it. (36)

The caffeine in coffee can also cause dehydration, which can make you feel tired, says Wu. “Caffeine does not replace the need for sleep; it only masks drowsiness, so underlying sleep deprivation can still cause fatigue.”

The Last Word From Sleepopolis

If you get plenty of time in bed at night, you may feel frustrated when you still feel tired during the day. Sleep needs are complex, and many, many factors can have a say in how you snooze. If you’re consistently sleeping well and still feeling tired during the day, a healthcare provider may serve as a great resource for investigating your sleep. They can help sort out what’s going on and work with you to make a plan for better sleep and health.

*Restrictions and regulations on supplements may vary by location. If you ever have any questions or concerns about a product you’re using, contact your doctor.

Sources

Wu, Chester, MD. Personal interview. November 2, 2024.

Wells, Audrey, MD. Personal interview. November 2, 2024.