Most people have pulled an all-nighter at least once in their lives, whether it was to meet a school or work deadline or to keep the party going until the morning.
The experience of going at least 24 hours without sleep, otherwise known as total sleep deprivation, obviously does not make you feel good the next day. The physical and mental repercussions are notable.
HuffPost spoke to sleep experts to find out what exactly happens to your body and mind when you pull an all-nighter.
You fight your body’s natural drive to sleep.
Pulling an all-nighter requires you to fight your body’s natural drive to sleep by making use of “wake-promoting factors” and avoiding “sleep-permissive factors,” said Roy Raymann, the vice president of sleep science and scientific affairs at Carlsbad, California-based SleepScore Labs.
“Wake-promoting factors include using caffeine, being in a colder environment, being in a well-lit room with plenty of blue-enriched light, and standing,” he said, adding that sleep-permissive factors include darkness, a warm comfortable temperature, reclining and closing your eyes.
Your body skips its recovery period.
When you skip a full night of sleep, your body has missed out on a much-needed opportunity to relax, recharge and recover.
“During the night, all kinds of restorative processes happen to bring you back to shape for the next day,” Raymann said. “Cells and tissues are repaired, toxins are removed from your brain, memories and emotions are dealt with and stored and the fatigue that you have been building up during daytime is reduced.”
Pulling an all-nighter or just getting a limited amount of sleep means that this recovery process doesn’t happen or isn’t executed to its full extent, leaving you unrefreshed.
“Cognitive performance degrades and mood can suffer,” said Nate Watson, co-director of the University of Washington Medicine Sleep Center and a SleepScore Labs advisor. “The glymphatic system, which removes the byproducts of a day’s worth of activity from the brain, is not able to perform its function.”
Stress hormones spike.
“When you’re not getting sleep, you’re running on stress hormones like adrenaline and cortisol, so stress levels rise,” said Jon Caulfield, a dentist in Littleton, Colorado, who focuses on airway, sleep and TMJ disorders and a board member and national instructor with the American Sleep and Breathing Academy.
“Sleep loss can cause stress and anxiety,” echoed Terry Cralle, a registered nurse and certified clinical sleep educator in the Washington, D.C. area who serves as a spokesperson for the Better Sleep Council. Cralle cited a recent study from the University of California, Berkeley, found that one sleepless can boost anxiety levels up to 30%.
This can be a vicious cycle: Stress and anxiety often cause people to have trouble sleeping, but then sleep deprivation increases stress and anxiety levels. And around and around you go.
Focus and accuracy drop.
“It has been postulated that even during a single night of sleep deprivation, the microstructures in your brain can change,” Raymann said. “Also, there’s now more evidence that during the night you’re getting a brain wash to remove all the debris and toxins that accumulated in your brain during the day. Both these changes ― micro-structure and no brain wash ― lead to impaired communication between your brain cells.”
This impaired communication between brain cells hampers your ability to pay attention or work at an optimal level. A 2007 study from St. Lawrence University in Canton, New York, found that pulling all-nighters was associated with lower grade point averages.
“Sleep deprivation affects your prefrontal cortex, which affects your cognitive abilities. Think of it as being impaired.” Cralle said.
Many experts have even compared sleep deprivation to drunkenness, which is why drowsy driving is so dangerous.
“In addition to a lack of focus, which many call brain fog, there’s a lack of accuracy. You’re likely to get things wrong on a test or miss a shot if you’re playing sports,” said Raj Dasgupta, assistant professor of pulmonary and sleep medicine at the University of Southern California.
This is why it’s dangerous to drive or operate heavy machinery while sleep deprived. You’re more susceptible to injury or accident.
In the wake of sleep deprivation, “the next day you will be less productive. Everything costs more time and takes more effort, and you are likely to make errors,” Raymann said.
He added, “My first mentor during my PhD taught me the wise lesson, when he saw me still late working at my desk: ‘Whatever you try to do at the end of the day after a busy day will cost you a lot of effort and time, and will even most likely lead to something you will not be happy with the next day. Go home, relax and get some sleep. During the next morning, you will resolve that task in a breeze.’”
“Sleep deprivation’s effect on working memory is staggering,” David Earnest, a professor with the Texas A&M College of Medicine, said in a 2016 report about the effect of all-nighters on health. “Your brain loses efficiency with each hour of sleep deprivation.”
Research has suggested that sleep plays a major role in memory consolidation, the process of short-term memories moving to long-term storage. When you pull an all-nighter, this process is disrupted, and memory recall suffers.
You’re likely to make poor decisions.
The prefrontal cortex is also linked to decision-making, so sleep deprivation can lead to poor judgment.
“Decision-making becomes impulsive,” Watson said. “We become less able to assess the potential negative consequences of our decision-making.”
You become irritable.
It’s hardly a surprise that people are cranky after not sleeping for a full night. Indeed, sleep deprivation often leads to a bad mood.
“Your interaction with people will be more blunted, and you might become easily annoyed or irritated,” Raymann said. “You will also likely look more tired.”
Your immune system is compromised.
Sleep deprivation can affect your body’s production of cytokines, which play a big role in your immune response. That could lead to a serious case of the sniffles down the road.
“When you’ve stayed up all night, your immune function is impaired,” Cralle said. “It could leave you susceptible to getting sick.”
You get hungry.
“Pulling an all-nighter leads to a leptin-ghrelin hormonal imbalance,” Cralle said.
Ghrelin is the body’s “hunger hormone” that increases appetite, while leptin is the “satiety hormone” that inhibits hunger.
“Your leptin levels are reduced and ghrelin is elevated when you’re sleep-deprived,” Cralle said, noting that many people feel very hungry after pulling an all-nighter.
You accumulate sleep debt.
When you don’t get enough sleep, you amass sleep debt. This is certainly true when you go more than 24 hours without sleep.
Sleep debt refers to the difference between the number of hours of sleep you should be getting and the amount you actually get. Chronic sleep debt has been linked to increased risks of obesity, heart disease, stroke, and diabetes.
All-nighters mess with your circadian circadian rhythm, but it’s possible to get back on track. However, if sleep deprivation becomes more than a one-off thing, consider seeking treatment for chronic sleep insufficiency.