Catching yourself yawning after lunch? You’re not alone. Up to 45 percent of people report feeling tired, especially in the afternoon. But what’s really going on behind the scenes when you’re suddenly reaching for sugary snacks or coffee to try and give you an afternoon boost?
Below, learn some causes of afternoon tiredness—and most importantly, what you can do about it.
Why Am I So Tired in the Afternoon?
Sometimes, it’s easy to power through a morning after a bad night’s sleep on adrenaline alone. But post-lunch, you’re ready for a nap.
This is partly because of sleep’s effect on cortisol, which regulates your energy and the stress response. Cortisol is naturally higher in the morning, but after poor sleep, it’s even higher. This can give you the tired-but-wired sensation that crashes as the day progresses.
It’s not always about how long you slept, either. The quality of your sleep is important for maintaining stable energy levels throughout the day.
If your sleep is fragmented or your sleep architecture is off, your body may not fully recover. This can make it harder to stay alert, focus, and power through tasks, especially in the afternoon when most people’s energy levels naturally wane.
| Member Tip: Get a high-level Sleep Score and detailed sleep insights every morning when you track your sleep with Oura. See your sleep stages, latency, restfulness, and more. |
Common Causes of Afternoon Energy Crashes
Poor Quality Sleep
What was the quality of your sleep like last night? Without the right data, it’s difficult to know. You may have remembered waking up a couple of times because your dog barked, but you don’t know how long it took you to fall asleep, or how much deep sleep you got.
Multiple factors contribute to your Oura Sleep Score and your overall sleep quality, ranging from how quickly you fell asleep to how much you tossed and turned during the night.
This helps you gauge how well you slept. Remember, it’s not all about the duration!
There are many possible causes of low-quality sleep, including:
- A hot bedroom
- Noise
- A heavy meal before bed
- Light exposure
- Caffeine or alcohol (we’ll come to this!)
READ MORE: 6 Surprising Bad Sleeping Habits & How to Break Them (for Good)
Blood Sugar Crashes
Sugar crashes—commonly associated with fatigue, irritability, cravings, and difficulty concentrating—happen most commonly within four hours after eating, usually if you have a meal high in sugar or simple carbohydrates (like fruit juice, baked goods, white rice, or pasta).
When you eat something high in sugar, your blood glucose spikes. Your body responds by releasing insulin to bring your blood glucose back down, which can cause it to drop too low.
The sudden drop in blood sugar is called reactive hypoglycemia, often referred to as an energy crash because of how it makes you feel.
Stress
Stress doesn’t just keep you up at night, it drains your energy the next day, too. Research from the American Psychological Association shows that people with high stress levels sleep about an hour less per night than those with low stress. And even if you are getting enough hours, stress can still disrupt your sleep quality.
Why? When your body is in a constant state of fight-or-flight, your stress response system—the hypothalamic-pituitary-adrenal (HPA) axis—stays activated. This can throw off your cortisol rhythm, make your heart work harder, and suppress immune function. You might not notice it right away, but over time, this chronic strain can leave you feeling run down, foggy, and persistently tired—even after what you thought was a full night’s sleep.
READ MORE: How Stress Affects Your Sleep
Too Much Caffeine
Caffeine may give you a quick energy boost, but it often comes at a cost. It triggers a release of adrenaline, which signals your liver to dump glucose into the bloodstream—causing a spike in blood sugar, followed by a crash once the effects wear off. Add refined sugar to the mix (hello vanilla latte), and that crash can hit even harder.
Beyond blood sugar, caffeine can quietly sabotage your sleep. With a half-life of 5 to 7 hours, even that 3 pm pick-me-up might still be circulating when you’re trying to fall asleep. Oura members who tag “late caffeine” show a 2% decrease in light sleep—enough to leave you dragging the next afternoon.
Over time, daily caffeine use can also lead to dependency. When your brain adjusts to regular caffeine, it suppresses adenosine—the neurotransmitter that makes you feel tired. But once the caffeine wears off, especially overnight, the adenosine rush returns, making you feel groggy first thing in the morning.
| Member Story: Oura member Jussi L. had perpetually low energy, so he changed his diet. „Instead of too much meat, pasta, and potatoes, we returned to rice, fish, vegetables, and fruits. Now I eat just a little porridge and a lot of fruit in the morning as breakfast, and then my lunch is filled with home-cooked Japanese meals with a load of fish, miso soup, and green veggies.“ |
Vitamin Deficiencies
Low energy isn’t always about sleep or stress—sometimes, it’s a sign of a nutrient deficiency. Several key vitamins and minerals play a central role in energy metabolism, red blood cell production, and oxygen transport. When levels are low, fatigue can follow.
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Iron is essential for producing hemoglobin, which carries oxygen throughout your body. Low iron (or iron-deficiency anemia) is one of the most common causes of persistent tiredness, especially in women of reproductive age.
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Vitamin D supports immune and neuromuscular function. Deficiency has been linked to daytime sleepiness, poor sleep quality, and mood changes.
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Vitamin B12 and folate are critical for red blood cell formation and neurological health. A deficiency can lead to fatigue, brain fog, and low mood.
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Magnesium plays a role in energy production and muscle function. Low levels are associated with poor sleep and increased feelings of exhaustion.
Waking Up in the Wrong Sleep Stage
Many people use an alarm clock to wake up in the morning. Unfortunately, your alarm clock isn’t synced up with what stage of sleep you’re in. As a result, it can wake you up in the middle of a deep sleep stage, causing sleep inertia.
Sleep inertia is a normal physiological response to waking up from deep sleep, characterized by feeling groggy and tired, regardless of how much sleep you’ve had.
It’s believed to be a protective mechanism. During deep sleep or REM sleep, your brain is in a state of reduced activity. Just because you wake up suddenly doesn’t necessarily mean your brain does. For some, this feeling can last up to an hour.
READ MORE: Why Do I Wake Up Tired? How to Feel More Alert in the Morning
Hormonal Changes
Hormones are your body’s chemical messengers—when they’re in flux or imbalanced, you can experience fatigue. That’s why women often report feeling tired leading up to and during their period. Similarly, women who are pregnant or nursing may also experience tiredness and require more sleep.
Medical Conditions
Thyroid disease, heart disease, and depression are conditions that can cause persistent tiredness, regardless of how much sleep you’re getting. Speak with your medical provider if you are experiencing consistent, unexplained tiredness.
Intense Physical Activity
People with active jobs or lifestyles can feel tired during the day. Intense exercise, for instance, can lead to fatigue due to the depletion of adenosine triphosphate (ATP), glycogen, and neurotransmitters that are released during your workout. This is why you might feel like you need to take a nap after a tough workout!
How To Stop Feeling Tired: 9 Tips For Better Afternoon Energy Levels
Tired of feeling tired? Follow these tips to help you overcome your mid-afternoon slump.
1. Focus on Sleep
Feeling energized in the morning starts the night before. Your tiredness will persist if you’re sleeping poorly. By focusing on winding down in the evening and creating a sleep-conducive environment, you can improve the quality and duration of your sleep to improve your daytime energy levels.
Most people aren’t aware of how much they tossed and turned during the night or whether they got enough restorative deep sleep. Using Oura can help you better understand your sleep so you can paint a picture of what may be contributing to afternoon energy crashes.
2. Eat Well-Balanced Meals
Sugar isn’t the enemy! While many blood sugar-spiking foods are nutritious, adjusting your meals to focus on healthy fats, proteins, and whole grains can help prevent afternoon energy dips. Healthy fats slow sugar absorption, reducing spikes and crashes. Proteins offer steady energy and support stable blood sugar. Whole grains, rich in fiber, are digested slowly, maintaining consistent energy.
| Member Tip: Let Oura Meals unpack how well your choices are fueling you, so you can feel your best each day. Beat cravings and energy slumps, identify nutritional imbalances, and stay on track toward your goals. |
3. Consider Meal Regularity
Skipping meals, especially breakfast, can leave your blood sugar low. When you finally eat a larger lunch to make up for the missed meal, it can cause a rapid spike in your blood sugar levels. For stable blood sugar, aim to eat small meals every few hours.
4. Skip the Caffeine
Experiment with cutting caffeine for a week and see if it improves your sleep and, by default, your daytime energy levels. That doesn’t mean you have to be caffeine-free forever, but taking a short break and re-regulating your sleep and caffeine sensitivity can be beneficial.
| Member Tip: Try Experiments on the Oura App where you can test how late-afternoon caffeine affects your sleep and recovery. When you complete an experiment, you’ll receive an Experiment Report with the results of how your scores or contributors were affected. |
5. Eat a Light Lunch, Like the Finns!
Founded and headquartered in Finland, we get a lot of inspiration from the Finns who work at Oura. Finns tend to opt for a light lunch—commonly soup, salad, and plenty of fish, and this approach might be a good idea for keeping your blood sugar regulated.
Eating a lighter lunch can also help you avoid sugar crashes because it prevents large spikes in blood sugar that often come with heavier, more carb-dense meals. They’re also easier for your body to digest, meaning less energy is spent on metabolizing your food, leaving more energy available for you to focus and stay alert.
6. Take a Midday Nap
Sometimes you’re just tired—perhaps you’re at a certain point in your cycle or you’ve had a particularly taxing day. If you have the ability to, take a short nap. Even 20 minutes of midday shuteye can give you an energy boost!
LEARN MORE: How Long Should You Nap?
7. Manage Stress
Taking 5-25 minutes out of your day to practice some relaxation techniques like meditation or breathwork can combat stress and brain fog and give you a boost of natural energy.
| Member Tip: Access Explore content on your Oura App to follow guided meditations and breathing exercises. |
8. Take a Walk or Light Jog Outside
How much time do you spend inside? While it’s not always possible to get outside, if you can, it’ll help reduce tiredness. Not only are you getting daylight in your eyes to help reset your circadian rhythm, but doing aerobic exercise increases blood flow and oxygen to the brain to help you wake up.
9. Make Time for Exercise Recovery
Doing back-to-back intense workouts can be counterproductive, leaving you feeling tired for the rest of your day’s activities. Taking recovery days between tough workouts can help prevent the energy dip (and help your performance!).
READ MORE: How Sleep Helps Muscle Recovery and Growth