Why do i feel less tired with less sleep

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

It's normal to wake up groggy or desire a mid-afternoon snooze. What's not so normal is consistently feeling tired throughout the day.

Low energy levels put a damper on your mood, creativity, and willpower, making it more difficult to check off your to-do list. If you find yourself regularly yawning, take stock of what's causing your daytime tiredness and learn how to feel more awake.

Below, we’ll dive into why you might be feeling so tired and what you can do to boost your energy levels.

‍

Why do I feel tired during the day?

How can I make myself feel more awake?

‍

Why Do I Feel Tired During the Day?

Before we share tips on how to feel more awake, let’s find out what's stopping you from being your best.

Feeling more awake during the day boils down to two things: low sleep debt and circadian alignment. Even if just one of these things is thrown off, you’ll likely feel low energy levels during the day.

Here’s what they are and how they work.

Sleep Debt

Caption: The RISE app tells you how much sleep debt you have. 

Sleep debt refers to the amount of sleep you’ve owed your body over the past 14 days. But, how does sleep debt exactly relate to staying awake when it's bright outside?

Two words: Sleep pressure. It’s our biological response that encourages us to go to bed and get the rest we need. Sleep pressure builds up during the day (courtesy of the drowsiness-inducing chemical called adenosine) and subsides at night in a process called the homeostatic sleep drive. Put it this way — the longer you're awake, the more adenosine accumulates in your brain to amplify sleep pressure.

The only way to relieve sleep pressure is to get enough sleep.

Unfortunately, when you don't meet your sleep need — the genetically determined amount of sleep you need each night — you aren’t easing sleep pressure. Instead, you’re accruing sleep debt. This sleep deprivation directly impacts how you feel during the day — think increased morning sleep inertia (i.e., you wake up feeling groggier) and lower energy levels.

So, if you’re constantly feeling sluggish and tired throughout the day, high sleep debt may be to blame.

You can work out how much sleep debt you’re carrying with the RISE app. RISE first works out your unique sleep need, so you have a number to aim for each night. It then calculates the amount of sleep debt you have. We recommend keeping this below five hours to feel and perform your best, and improve your energy levels each day.

That said, your sleep debt isn't the only factor that can affect your energy levels.

Circadian Rhythm — The Other Missing Piece

Aside from sleep debt, your circadian rhythm also plays a huge part in how awake you feel. Fondly referred to as your body's internal clock, your circadian rhythm tells you when it's time to turn in or to get up. 

If you regularly sleep at different times, you’ll be throwing your circadian rhythm out of whack, causing low energy levels during the day and difficulty sleeping come nighttime. 

Your circadian rhythm is also the reason why your energy levels fluctuate throughout the day.

PSA: It's absolutely normal for your energy levels to peak and dip as the day wears on. In fact, there's one dip everyone goes through, no matter if you've had a good night’s sleep or eaten a healthy lunch.

The Afternoon Slump

When afternoon arrives, you're probably yawning at your desk and trying to keep your eyes open. In other words, it's the dreaded afternoon slump. 

But, here’s the thing: The afternoon dip is natural and expected. Sure, super early birds may experience a noon-ish dip, and extreme night owls usually feel the effects in the late afternoon. But, no matter your biological sleep-wake inclinations (also known as your chronotype), everyone goes through the afternoon slump — and no, it isn’t due to your lunch. 

After all, you’ve been riding high on your morning peak and expending immense brainpower. What goes up must eventually come down. (That said, a high-carb lunch can worsen the afternoon slump, as it spikes your blood sugar levels and triggers an energy crash.)

Science explains the afternoon dip occurs due to a temporary fall in circadian alerting signals. Light prompts your circadian master clock to release circadian alerting signals in steadily increasing levels from the moment you rise. These signals promote wakefulness to counter sleep pressure.

Corresponding to the rise and fall of your circadian rhythm, the level of circadian alerting signals naturally dips at certain times of the day. For many, the first of two notable dips coincides with the hours just after lunch, resulting in your mid-afternoon slump. During this time, your lowered circadian alerting signals combine with rising sleep pressure, which explains the intense sleepiness and yawns.

So, if you’re feeling sleepy in the afternoon, it may just be your natural biology at play. 

Sleep Debt and Circadian Rhythm Team Up

While your sleep debt and circadian rhythm work independently, they both affect how awake you feel during the day.

As your circadian rhythm dictates your sleep and wake times, it invariably determines your sleep length. Sleep times not aligned to your natural rhythm — characterized by late bedtimes and early wake times — promote circadian misalignment and inevitably insufficient sleep. In other words, you're carrying high sleep debt, which leads to more difficulty staying awake during the daytime.

At the same time, high sleep debt does a number on your energy levels, too. While it's true that your circadian rhythm directly influences your energy fluctuations, sleep deprivation shrinks your peaks and amplifies your dips, leading to an overall drop in productivity and performance.

In essence, lowering your sleep debt and practicing circadian consistency helps you feel more awake and energetic during the day.

RISE predicts your circadian rhythm each day based on things like your phone use behavior and inferred light exposure. This way, you can see when your peaks and dips in energy are coming, and plan for them by scheduling harder tasks when you naturally have more energy, and saving easier tasks for when you’re naturally more tired. 

‍

How Can I Make Myself Feel More Awake?

If you want to be at your best, follow these science-based tips and learn how to feel more awake.

1. Lower Your Sleep Debt 

As we explained above, sleep debt is one of the biggest things determining your energy levels each day. Most of us know how important sleep is, but not many of us know how much of it we need exactly.  

Everyone’s sleep need is different, too. The average sleep need is 8 hours 10 minutes, plus or minus 44 minutes or so, but 13.5% may need 9 hours of sleep or more a night.

Once you’ve found out your sleep need with RISE and seen how much sleep debt you’re carrying, you can work to pay down this debt back if it’s more than five hours. 

You can do this by: 

• Taking naps 
• Going to bed a little earlier 
• Wake up a little later 
• Maintaining good sleep hygiene — this will improve your sleep efficiency (or how long you spend in bed actually sleeping), meaning you get more sleep overall. 

2. Sync Up with Your Circadian Rhythm 

Even if you’re meeting your sleep need each night, you’ll still feel low on energy if you’re living out of sync with your circadian rhythm. You can use the RISE app to see a prediction of your circadian rhythm each day. This’ll help you determine the best times to go to sleep, wake up, and when you’ll most likely be more and less productive. 

If you’ve got control over your schedule, you can sync up when you do these things with your natural biology. By that we mean plan demanding tasks for your energy peaks and easier tasks for your energy dips, making the most of each.  

What are dip-friendly activities? Think tasks that don't need much brain power, whether it's watching a lecture or clearing admin work. For more inspiration, check out our Sleep Guide to find out how you can make the most of your energy dip.

3. Nap (Responsibly) 

Napping is an effective way to relieve sleep pressure, shrink sleep debt, and increase alertness. But there's a science to napping, taking into account your individual needs and circumstances.

• Replacement napping: This type of napping is conducive to paying down sleep debt. Power naps of 10-20 minutes boost energy for 1-2 hours sans the wake-up drowsiness. Deeper naps of 40-90 minutes provide longer energy spurts but are much likelier to incur grogginess.
• Prophylactic napping: You can also nap in anticipation of sleep deprivation. This is especially popular among the night-shift crowd but works just as well in any circumstance when you know you won’t be meeting your sleep need. Not only does it keep sleep debt low, but it also optimizes alertness, mood, and performance better than a cup of coffee.
• Appetitive napping: This is the proverbial pick-me-up when you aren't napping to counter sleep deprivation, now or later. It may seem frivolous, but science shows appetitive naps — on top of a good night's sleep — offer significant health benefits in terms of mood, alertness, and cognition.

Timing is key when it comes to naps, however. Nap too close to bedtime and you’ll risk having trouble falling asleep at night, which could add to your sleep debt and make you feel tired the next day. To stop this from happening, keep naps to your afternoon dip in energy.

4. Prime Your Sleep Environment

Follow the first rule of feeling more awake  (i.e., keep sleep debt low) and get enough sleep every night. To start, check your sleep environment and prime it for a good night's sleep.

Here’s what you can do to enter dreamland more smoothly:

• Keep it cool: Your core body temperature naturally drops in preparation for sleep. Keep your bedroom between 65 and 68 degrees to simulate this change. Also, a hot shower or bath before bed is a simple thermoregulation hack to quickly shift your core body temperature from hot to cold. This can help you fall asleep faster and enjoy deeper sleep.
• Keep it dark: Artificial and natural light are the greatest circadian cues for wakefulness, meaning they can actually wake you up and delay when your body falls asleep. It's best to block out all light sources with an eye mask and light-blocking curtains or blinds. You should also dim the lights and put on blue-light blocking glasses 90 minutes before bed to help your brain make enough of the sleep hormone melatonin for a good night’s sleep.
• Keep it quiet: Noise keeps you from restful slumber through increased sleep latency (the time it takes to fall asleep) and sleep fragmentation (how often you wake up during the night). We recommend wearing earplugs and soundproofing your room with carpet and noise-blocking curtains.

We understand it can be difficult to implement new changes and follow through with them. That’s why RISE has an in-app section called “Habits” to make the habit-forming process as effortless as possible. Simply go to Habits in the app and add the following activities to your Energy Schedule:

• "Wear blue-light blocking glasses"
•  "Wear a sleep mask"
• "Environment check"

This way, RISE can send you prompts to make the above changes that will soon become second nature to you. 

5. Keep a Consistent Sleep Schedule 

Remember how circadian misalignment disrupts your sleep patterns and hikes up sleep debt?

Nip that in the bud with a consistent sleep schedule tailored to your chronotype — are you a morning lark, a night owl, or somewhere in between? If possible, go to bed when your body tells you to and keep to a consistent wake time (that accounts for your sleep need), even on the weekends. Not only will you benefit from increased energy during the day, but you'll also find it easier to fall asleep each night. If your chronotype is at odds with when you need to wake up, consider resetting your circadian rhythm.

Keep a careful eye on social jetlag — when your body clock is at odds with your social clock. This often happens when we stay up an hour or two later on the weekends and hit the snooze button the next morning, only to snap back into early wake ups come Monday morning. As tempting as sleeping later on the weekends is, try to keep the times you go to bed and wake up the same.

6. Get Bright Light

 Light can disrupt your sleep at night, but it can help make you feel more awake come morning. Aim to get at least 10 minutes of light exposure as soon as possible after waking, and make that 30 minutes if it’s a cloudy day or you’re getting light through a window. This can set you up for increased energy levels for the rest of the day. 

7. Curb Anxious Thoughts with a Wind-Down Routine

Anxiety doesn't just increase sleep latency (you take longer to enter dreamland) and fragmentation (you’re less likely to sleep through the night). In fact, this negative emotion is also linked to sleep disorders like insomnia, which downgrades daytime alertness.

Fortunately, you can take steps to stop anxiety from overwhelming you with a wind-down routine. Mentally decelerate just before bed to slow down your brain and signal to it that it’s time for sleep. Find what works for you, whether it's writing tomorrow's to-do lists, spending quality time with family, or rewatching old movies.

Relaxation techniques also help lower stress and anxiety to lull you to sleep more easily. RISE offers scientifically proven relaxation programs — think Diaphragmatic Breathing and Relaxing Sounds — which you can play in bed at night.

All this will help you meet your sleep need each night, leading to increased energy the next day.

8. Cold Water

If you need to feel more awake instantly, head to the restroom and splash some cold water on your face — it raises your heart rate, blood flow, and metabolism to wake up your body. Plus, a cold shower can be an energizing part of your morning routine and it acts as a mood-lifter by relieving gloomy thoughts.

9. Caffeine

A cup of espresso is the quintessential pick-me-up, whether it's in the morning to neutralize sleep inertia and jumpstart your day or in the afternoon to combat your energy dip. Caffeine works by temporarily blocking adenosine receptors in your brain, meaning the sleepiness-inducing chemical can’t do its job. 

That said, caffeine clings to your system for up to 12 hours, so be wary of how late you drink it to ensure it doesn't disrupt your sleep that night.

You may think decaf is a good alternative for an afternoon cup of joe. Unfortunately, it isn't entirely caffeine-free. If you're sensitive to caffeine, decaf beverages can still throw your sleep routine off-balance and incite higher sleep debt.

RISE helps you determine when you should cut off your caffeine consumption based on your unique biology. Go to Habits and add the "Limit Caffeine" reminder to your Energy Schedule.

10. Exercise

Nothing's better than a rush of endorphins to battle tiredness if paying down sleep debt isn’t immediately possible. Physical activity also increases your heart rate and body temperature to boost your energy levels. Scientific literature recommends low- to moderate-intensity workouts to boost energy during the day and sleep better at night. Go for a morning walk to get some fresh air or cycle during your afternoon dip.

Just like with caffeine and naps, exercising too close to bedtime can make it harder to fall asleep, so aim to keep your intense workouts to earlier in the day.

11. Avoid Large Evening Meals

Your diet impacts your energy levels in two significant ways: 

• It can undermine your sleep (which will negatively impact your wakefulness)
•  It can directly affect how awake you feel in and of itself.

Relating to the first point, large evening meals inflate the risk of abdominal discomfort, indigestion, and acid reflux when you lie down. In other words, it’s harder for you to drift off to sleep after overeating. RISE can tell you when to avoid large meals to stop this from happening.

But it's not just how much you eat at night — the type of food also matters, which is where the second point comes in:

• Research shows a high-carbohydrate, high-fat food intake is linked to poor sleep, possibly worsening morning grogginess.
• On the other hand, milk products, fish, fruit, and vegetables may help you drift off more easily.
• A 2020 medical review also highlights tryptophan, melatonin, and phytonutrients as slumber-promoting micronutrients. To get these micronutrients, try incorporating foods like turkey, tart cherry juice, carrots, tomatoes, berries, and kale in your diet.

12. Abstain from Alcohol and Nicotine

Alcohol consumption and cigarette smoking do more harm to your sleep than good.

• Alcohol might promote sedation, but it also causes interrupted sleep and reduced REM (rapid eye movement) sleep. Simply put, you wake up more tired than usual.
• Nicotine also interrupts your sleep and inhibits slow-wave sleep (i.e., deep sleep in which your body repairs and rejuvenates itself). This translates into poor slumber and a vicious cycle of ever-growing sleep debt.

Overall, it's best to abstain from alcohol and nicotine — your sleep cycle will thank you for it. But, if you have to drink and/or smoke, do so a few hours before bedtime so it’s less likely to disrupt your sleep.

13. Drink a Glass of Water

For an immediate pick-me-up, turn to water. Research shows being even mildly dehydrated can zap you of energy, ruin your mood, and impact cognitive functioning. Plus, even just the act of getting up and walking to get water will give you an energy boost.

We’ve covered more ways to wake yourself up here. You can also use RISE to plan an energy boost. Choose from things like get light, take a nap, and exercise, and RISE will show you the best time in your schedule to do them. 

How to Feel More Awake Begins With Sleeping Better

Now you know how sleep debt and circadian misalignment can tank your energy levels, it’s time to make the necessary changes to your bedroom, sleep schedule, and wind-down routine to stop that happening. If you’re wondering how to stay awake during the day, our alertness-boosting tips can help you maximize your energy levels.

Once you’ve realized you can overcome the obstacles to feeling more awake, more energy is just within your reach. The RISE app can help by calculating your sleep debt and keeping track of it as you pay it back, and predicting your circadian rhythm each day helping you stay in sync. Plus, it can remind you when to do 20+ sleep-boosting habits to help you meet your sleep need each night, for optimal energy each day.

Why do I not feel tired after little sleep?

Can sleeping less make you less tired?

Do you feel more awake with less sleep?

Why do I have more energy when I don't sleep?