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How to Function on No Sleep When You Absolutely Have To

You can function on no sleep by getting out in sunlight, eating balanced meals, exercising, and taking a nap to get more energy. Catch up on sleep when you can.
Written by
Jeff Kahn, M.S., Rise Science Co-Founder
Reviewed by
Chester Wu, MD, Rise Science Medical Reviewer
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We bring sleep research out of the lab and into your life. Every post begins with peer-reviewed studies — not third-party sources — to make sure we only share advice that can be defended to a room full of sleep scientists.
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Updated Regularly
We regularly update our articles to explain the latest research and shifts in scientific consensus in a simple and actionable way.

How to Function on No Sleep? 

  • You can function on no sleep by getting out in natural light, exercising, and taking a nap. 
  • Sync up with your circadian rhythm to make the most of your natural peaks in energy.
  • The RISE app can predict your circadian rhythm each day, so you know when your natural peaks and dips in energy will hit. RISE can also recommend energy-boosting activities at the right times to get you through the day, and help you catch up on lost sleep so you’re back to functioning at your best as soon as possible.

It happens to the best of us. You’re out late with friends, up early with kids, or spend a night wide awake with insomnia. But you still need to work and be a functioning adult the next day. 

Below, we’ll dive into how to function on no sleep and how the RISE app can help you get through the day after a sleepless night and catch up on sleep when you can.

A Sleep Doctor's Advice

A Sleep Doctor's Advice

“When you’re trying to function on no sleep, try adding a workout to your day. A vigorous workout can be protective against certain negative impacts of sleep loss, but you’ll also be more at risk of injury when sleep deprived. If you’ve missed out on a lot of sleep, try a brisk walk or some gentle stretches instead to boost your energy and improve your next night’s sleep.”

Rise Science sleep advisor and medical reviewer, Dr. Chester Wu

1. Get Out in Sunlight 

Get out in natural light for at least 10 minutes in the morning. If it’s overcast or you’re sitting by a window, make that 15 to 20 minutes

If this is a daily habit for you (we recommend it!), get light at the same time you usually do each day, even if your sleep schedule is messed up. 

Morning light resets your circadian rhythm, or body clock, and suppresses the sleep hormone melatonin, helping you feel more alert. 

It also sets you up for a good night’s sleep that night, something you’ll need to recover from the sleep loss. 

For shift workers, 2023 research suggests morning sunlight can help you adjust to the day-night cycle after working a block of late or night shifts. 

Try getting out in natural light during the day, too. This can perk you up, improve your mood, and make evening light less disruptive to your sleep and circadian rhythm. 

A 2023 study even found automated lighting timed to help participants adjust to a night shift schedule helped improve performance during the night. 

Expert tip: If it’s dark out when you wake up, try sitting in front of a 10,000 lux light therapy lamp instead. Sit 16 to 24 inches from the lamp for 30 minutes. 

2. Exercise  

You might not feel like exercising, but high-intensity interval training (HIIT) can protect you from some of the negative health effects a lack of sleep can cause.

A 2022 study found HIIT helps stop the reduction in myofibrillar muscle synthesis (key for maintaining muscle mass) that can come with sleeping for four hours. 

And a 2021 study found HIIT can counteract the reduced glucose tolerance and mitochondrial respiratory function (energy conversion in your cells) from four hours of sleep

Another 2022 study found 30 minutes of aerobic exercise reduces the impairment of cognitive control that comes from an all-nighter. 

Plus, exercise releases feel-good endorphins (ideal as you’ll probably be feeling grouchy after no sleep last night) and triggers the alertness-boosting hormone cortisol for an energy boost.

Just be extra careful of injury. If you’re truly running on no sleep, gentle cardio or yoga is safer than an intense HIIT session or strength training. 

You can learn more about working out on no sleep here.  

Expert tip: Consider when you do your exercise. Morning exercise can help you get out in natural light and give you an energy boost for the workday. Your energy will probably be flagging mid-afternoon, so that’s a great time to get in some physical activity (as well as a nap). And if the only time you have is close to bedtime, go for something gentle, like yoga, so you don’t keep yourself up. 

Learn more about the best time to work out here.

3. Drink Caffeine Cautiously 

If you’ve had no sleep, or less sleep than you need, you’re probably craving an extra coffee or two, especially if you’re falling asleep at work

But while caffeine can help you feel more alert, it can also mess with your sleep that night, leading to even more trouble functioning the next day. 

A 2023 meta-analysis found caffeine can reduce your total sleep time by 45 minutes, and the closer to bedtime you consume it, the more it impacts your sleep. 

The same goes for the amount of coffee you drink, too. A 2023 study on financial traders using coffee to compensate for – but ultimately perpetuate – habitual sleep loss during the week, found the more coffee you drink, the more it cuts into your total sleep time. 

Enjoy coffee in the morning, but avoid caffeine about 12 hours before bed. RISE can tell you when to cut yourself off from caffeine to stop it from disrupting your sleep.

The Food and Drug Administration (FDA) recommends limiting your caffeine intake to 400 milligrams per day — about four 8-ounce cups of brewed coffee. Although, the amount of caffeine in a cup of coffee can vary widely, as can individual tolerance to caffeine.

If you don’t like coffee or can’t have caffeine, learn how to get energy without caffeine here.

RISE app screenshot showing when to limit caffeine
The RISE app can tell you when to stop drinking coffee each day.

RISE users on iOS 1.202 and above can set up their limit caffeine reminder here.

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4. Eat Healthy Meals 

Your hunger hormones get thrown out of whack after a sleepless night, so you’ll be hungrier and probably craving sugary snacks and junk food.

Resist the urge to reach for sugar or energy drinks to wake yourself up

Instead, fruits, veggies, healthy fats, protein, and complex carbohydrates like brown rice and lentils can provide a steady source of energy throughout the day — rather than a short-term sugar rush then crash.

Avoid large meals, which can make you feel more tired (especially in the afternoon), and try to eat your meals at your usual meal times to keep your circadian rhythm in check.

And stay hydrated with lots of water as dehydration can add to fatigue.

Expert tip: Eat a balanced breakfast rich in complex carbs that are slowly digested and absorbed. Research from 2022 found a high-complex carb breakfast leads to more morning alertness. Go for fruits, oatmeal, or whole-grain bread alongside healthy fats and protein. 

5. Sync Up With Your Circadian Rhythm 

Your energy naturally fluctuates throughout the day as part of your circadian rhythm, your roughly 24-hour body clock. You’ll have peaks and dips in your energy even when you get enough sleep. 

When you’re sleep deprived, your peaks in energy will be lower and your dips in energy will feel worse. But you can still use this to make the most of the energy you do have. 

RISE predicts the timing of your circadian rhythm, so you can schedule your day to match. 

Here’s what we recommend: 

  • Do your most challenging tasks during your energy peaks — usually mid-morning and early evening. 
  • Do easy tasks, take a break, or take a nap during your energy dips — i.e. the afternoon slump.

Even during your energy peaks, you won’t be at your best, so, if possible, reschedule any important meetings or big decisions to a day when you can get more sleep. Your feelings of connectedness, your career aspirations, and even your ethics all take a hit when you’re sleep deprived. 

You can sync RISE with your calendar so you never miss a productive energy peak and you’re not surprised when a dip hits. 

RISE users say it’s pretty spot on: 

“I’ve been using RISE for about a week and it’s been eye-opening to learn that the app can pretty accurately predict when I will have energy and when I will be struggling.” Read the review.

Expert tip: Syncing up with your circadian rhythm can boost your energy overall. Do this by keeping a regular sleep pattern, getting and avoiding light on a regular schedule, and eating meals at regular times. 

The RISE app can predict your circadian rhythm daily.

RISE users on iOS 1.202 and above can see their upcoming energy peaks and dips on the Energy screen here.  

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6. Take a Nap 

A nap can help you stay awake after an all-nighter. And you don’t need to head back to bed for long. Research shows a 10-minute power nap can boost energy and cognitive performance in sleep-deprived people. 

Got a workout planned? A 2023 systematic review found a 20-to-90-minute nap helps reduce impairments in athletic performance that can happen after a night of sleep loss. 

A longer nap may be beneficial. One study found a two-hour nap after an all-nighter helped increase participants’ alertness and performance, and it even reversed the increased cortisol the sleep loss caused. 

Just be sure not to for too long or too close to bedtime as you may struggle to sleep that night. We usually recommend keeping naps under 90 minutes, but after a night of no sleep, a longer nap may be beneficial. 

Take a nap during your afternoon dip in energy (if you’ve had no sleep it’s unlikely you’ll be productive during this time anyway). Check RISE for when this is each day.

Dr. Jamie Zeitzer, one of our sleep advisors and Co-Director of the Center for Sleep and Circadian Sciences at Stanford University likes to nap to get more energy. 

“I inherited a couch in my office and will take a nap!” 

7. Combine a Coffee and a Nap

When you really need to wake yourself up when tired — like when you’ve got an important afternoon presentation — try drinking a coffee right before taking a short nap. 

When you wake up, the energy-boosting benefits of caffeine and sleep should kick in together. 

Expert tip: We’d only recommend this when you’re really running on no sleep as you may be drinking coffee too late in the day and risk disrupting your next night of sleep. If you’re very sleep deprived, you may be able to fall asleep later that day no problem, but proceed with caution and only use this tip when you really need to perk yourself up.

The caffeine-nap combo can help when driving, but it’s much safer to pull over to avoid drowsy driving. Research suggests you have the same cognitive impairments after being awake for 18 to 20 hours as you would with a blood alcohol level of 0.1% — over the legal limit for driving in every state.

If possible, avoid driving or doing manual work or dangerous tasks after an all-nighter. Your alertness, judgment, and reaction times will be impaired and you’re more at risk of microsleeps — falling asleep for a few seconds, sometimes without even noticing. 

Learn how to feel more awake here.

8. Catch Up on Sleep Soon 

You can’t function well on no sleep, especially not long term. When you don’t get enough sleep, you start building up sleep debt. Sleep debt tanks your energy, well-being, and productivity, and can lead to serious health issues in the long run. 

You can pay back sleep debt by: 

  • Taking naps 
  • Heading to bed early 
  • Sleeping in later (keep this to an hour or so to avoid disrupting your circadian rhythm)
  • Improving your sleep hygiene (which can help you fall asleep faster and wake up less often, so you spend more time asleep in bed)

Try to catch up on sleep without messing up your sleep schedule too much. Several early nights and afternoon naps are better than one epic four-hour snooze at the weekend. 

The National Sleep Foundation’s 2023 guidelines say to keep a regular sleep schedule, but catch up on sleep at the weekend if needed. 

To help, RISE works out how much sleep debt you have and keeps track as you pay it back. The app also guides you through 20+ sleep habits to maximize your time in bed.

Learn how long it takes to recover from sleep deprivation here.

The RISE app calculates how much sleep debt you have.

RISE users on iOS 1.202 and above can view their sleep debt here.

Expert tip: If you know you’ve got an all-nighter coming up, lower your sleep debt beforehand to help you function better afterward. You’ll also have less sleep to catch up on. Try aiming for five hours of sleep debt or lower. 

One or two bad nights of sleep is nothing to worry about, but if you regularly get poor sleep and you’ve improved your sleep hygiene, reach out to a healthcare provider to get checked for an underlying health problem or sleep disorder like sleep apnea. 

Heads-up: We all need a different amount of sleep. This is known as your sleep need. When we looked at the sleep needs of 1.95 million RISE users aged 24 and older, we found it ranged from five hours to 11 hours 30 minutes.   

RISE can work out how much sleep you need a night, so you know what to aim for when you can get more sleep. 

The RISE app can tell you how much sleep you need.
How much sleep RISE users need.

RISE users on iOS 1.202 and above can view their sleep need here

Get Through the Day on No Sleep 

You don’t want to make a habit of it, but sometimes you need to function on no sleep. 

Whether you’ve pulled a true all-nighter or simply got less sleep than you need, try getting out in sunlight, exercising, and taking a nap to function better the next day.

RISE can help you sync up with your circadian rhythm — to make the most of the energy you do have — and pay back sleep debt — so you can get back to operating at 100%. 

It’s fast, too — 80% of RISE users say they feel more energy and get better sleep within five days. 

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Try 7 days free

The power behind your next best day

RISE makes it easy to improve your sleep and daily energy to reach your potential

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