The Difference Between Tired and Sleepy

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It’s mid-afternoon, and you suddenly feel like you’ve hit a wall. You desperately need a caffeine jolt so you can power through. Sound familiar? Feeling tired in the afternoon is pretty typical, and most of us aren’t immune. But what’s the difference between being tired and being sleepy? 

Turns out, there’s a big difference: “They’re two totally different constructs,” Dr. Shelby Harris, Sleepopolis’ director of sleep health, says. “Sleepiness is the irrepressible need for sleep — [if you’re feeling ] drowsy, or you can’t keep your eyes open… even lapses in attention here and there… those are all signs of sleepiness,” she adds. 

In contrast, fatigue is “feeling extremely tired [or] having no energy, but when you try to nap, you actually can’t, because you’re not necessarily sleepy,” she says. 

Not sure which one you’re feeling? That’s what we’re here for. Read on to figure out whether you’re sleepy or tired — and how to get good sleep either way. 

The Difference Between Feeling Sleepy and Feeling Tired 

Though many of us use the words interchangeably, feeling sleepy and feeling tired or fatigued are actually distinct. “There are many forms of fatigue, but not all of them involve sleepiness,” says Dr. Kent Sasse, M.D.

Feeling sleepy or drowsy is the feeling you get when you’re ready for sleep. Your eyelids may flutter, or you might feel like you could nod off. Usually, these feelings intensify the longer you stay awake, which is the result of a hormone called adenosine being released in the brain. This hormone modulates our need for sleep and gradually builds throughout the day so that we feel sleepy come bedtime. Combine it with melatonin, the hormone that’s released when it gets dark, and you’re more than ready for bed.

Feeling tired, or fatigued, on the other hand, isn’t necessarily related to feeling sleepy. You could feel physically or emotionally drained without feeling like you need a nap.

What Causes Sleepiness?

You may feel sleepy if you didn’t get enough sleep the night before or if you ate a big meal for lunch and experienced an insulin spike. What you ate can also play a role. Foods high in specific vitamins — like bananas — can also trigger production of melatonin, making you feel sleepy. As for that afternoon energy dive, it’s a normal part of the wake/sleep cycle regulated by the circadian rhythm in adults. Our wakefulness rhythm dips in the afternoon and rebounds in the evening, which is why it’s not unusual to feel your energy nose-dive around 3 p.m., only to get a second wind a few hours later.

Another cause of the afternoon sleepies can actually be your morning cup of coffee — interestingly, while caffeine blocks the effects of adenosine, production is still underway. Once the caffeine wears off, the build-up of adenosine hits and makes some people feel sleepy, even early in the day. 

What Causes Tiredness?

Feeling physically tired after a hard workout is a good example of fatigue, and so is feeling emotionally drained after a period of heavy concentration, like taking an exam. In both cases, you’re tired but not necessarily sleepy. If you’re feeling low on energy or irritable, you’re finding small tasks draining, or you’re having trouble focusing, you’re probably experiencing tiredness.

How to Avoid Feeling Sleepy Throughout the Day

If you’re struggling with keeping your eyes open during the day, there are a few best practices worth exploring.

  • Prioritize sleep at night with good sleep hygiene. Aim for 7 to 9 hours of good sleep every night. To make that happen, make a point of creating an intentional sleep environment that’s dark, cool, and quiet.
  • Minimize caffeine, alcohol, and heavy meals. Try to avoid alcohol in the evening. While it might help you fall asleep, it can lead to awakening in the night and interfere with REM sleep. Caffeine blocks the much-needed effects of melatonin and adenosine, especially if you’re indulging in the late afternoon or evening. Meanwhile, big meals eaten within two to three hours of bedtime can ramp up the digestive system, which can disrupt your circadian rhythm (and potentially lead to heartburn!).
  • Turn off the devices. Another melatonin killer? The blue light on your laptop, smartphone, or tablet! Make a point of avoiding blue light at least one hour before bed to better promote sleep.
  • Spend some time in the sun. Since the body’s circadian rhythm responds to light, increasing your sun exposure during the day can help you feel more alert. 

How to Avoid Feeling Tired Throughout the Day

Unlike avoiding feeling sleepy, “avoiding fatigue during the day is not a one-size-fits-all solution,” says Sasse. “People are biologically different, and some will experience fluctuations in cortisol, insulin, leptin, vasopressin, and likely many other key regulators that influence fatigue.” Still, many of the same best practices apply, like good nighttime sleep, regular exercise, hydration, and nutrition, along with avoiding an overly-large midday meal. 

One of the best ways to combat feeling tired throughout the day is movement. Even moderate walking will boost the circulation of oxygen in your body, supporting mitochondrial function and helping you feel more energized. Try talking a short walk after lunch—you might be surprised at how energized you feel.

Proper hydration and nutritious meals that incorporate fiber, healthy fats, lean proteins, and complex carbohydrates also go a long way toward keeping you feeling alert. By keeping your blood sugar stable, you can avoid the insulin spikes that leave you feeling drained. Reach for foods like low-sugar fruits, vegetables, nuts and seeds, eggs, and chicken or fish.

Could Feeling Sleepy or Tired Be a Sign of a Sleep Disorder? 

If your feelings of sleepiness or fatigue aren’t overly consistent, or limited to the afternoons, it’s likely not an issue. But “chronic fatigue and sleepiness can most definitely be a sign of a sleep disorder,” says Sasse. 

Obstructive sleep apnea is the most common sleep disorder, and it severely impacts sleep quality. It’s also largely under the radar — up to 80 percent of cases remain undiagnosed.

“Any fatigue or sleepiness that feels excessive, interferes with work or relationships or quality of life, deserves a mention to your doctor,” says Sasse.

The Last Word from Sleepopolis

Understanding the difference between feeling sleepy and feeling tired or fatigued can help you pinpoint potential causes — and zero in on the real culprit behind your afternoon energy slump. Whatever you’re experiencing, prioritizing good nighttime sleep, exercise, hydration, and nutrition can go a long way in keeping your daytime energy levels up.

Jessica Timmons
Jessica Timmons has been working as a freelance writer since 2007, covering everything from pregnancy and parenting to cannabis, fitness, home decor, and much more. Her work has appeared in Healthline, mindbodygreen, Everyday Health, Pregnancy & Newborn, and other outlets. She loves weight lifting, a good cup of tea, and family time. You can connect with her on her websiteInstagram, and LinkedIn.