A full night’s rest is key for waking up alert and energized for the day. But a wave of social media habitués, across platforms from TikTok to Reddit, have recently boasted a contrarian-tinted trend: avoiding sleep to feel more awake. Many report feeling weirdly wired—and paradoxically more productive—despite snoozing for three to four hours instead of the seven to nine hours most experts recommend for adults.
But sleep scientists say the energy jolt some people claim to experience after acute sleep deprivation stems from a natural but fleeting sense of alertness that the brain uses to temporarily cope with insufficient rest. “I can’t deny that, subjectively, people are feeling kind of wired,” says Jamie Zeitzer, a sleep medicine researcher at Stanford Medicine. “Physiologically speaking, that’s not happening. They’re not actually more alert.”
Still, social media and grind culture continue to romanticize the practice. And famous and infamous entrepreneurs have long attributed their success to prioritizing work over sleep. In his early years building Microsoft, Bill Gates often competed with co-workers to see who could run on the least amount of sleep. Elon Musk frequently pulled all-nighters and slept on the Tesla factory floor. That company’s namesake, Nikola Tesla reportedly slept no more than two hours a night while working on an invention.
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Sleep scientists, however, want to make the matter clear: no type of sleep deprivation is ultimately good for you. “Our biology requires sleep, and there is no way around it,” says Eti Ben Simon, a neuroscientist and sleep researcher at the University of California, Berkeley.
Scientific American spoke further with sleep experts about what happens in the brain when it runs on limited sleep and how this can affect health.
Triggering Survival Mode
When the brain senses sleep disruption, it protectively acts as if something might be very wrong, and survival instincts kick in. The body produces a physiological reaction to keep the brain alert and energized, Ben Simon explains. The network of our sympathetic nervous system produces the fight-or-flight response, which uses stored energy to react against approaching predators.
A single night of sleep deprivation is a stressor, which acts via the central nervous system to activate the hypothalamic-pituitary-adrenal (HPA) axis. This circuit between the brain and the adrenal glands triggers the stress response, and the adrenal glands secrete the wakefulness-promoting hormones cortisol and adrenaline. This in turn prompts the liver to release sugar into the blood, creating an immediate energy supply during the fight-or-flight response.
“That level of energy people might feel after a short sleep might actually be the stress response the body and brain are provoking to fight off sleep loss,” Ben Simon says. Zeitzer adds that the rise in cortisol from insufficient sleep is only a small bump, just enough to hide fatigue for a few hours after waking.
The energy boost from the sympathetic nervous system is temporary, and it does not mean people’s brains are fully functional, however. Ben Simon says sleep loss experiments show people’s memory and attention are immediately impaired after a single night of sleep deprivation.
Sleep Inertia
Researchers generally describe five stages of the sleep cycle: wakefulness, three phases of nonrapid eye movement (NREM) and one phase of rapid eye movement (REM). Clinical psychologist Michael Breus, who now works with commercial approaches to improving sleep, says the stage at which a sleeper wakes up can affect how they react to being abruptly roused and subjectively refreshed.
“The disconnect from the environment is so profound that if you wake up someone from deep sleep, it takes them longer to realize where they are and what has happened versus if you wake them up from light sleep,” Ben Simon says. And the longer a person sleeps, the greater the chance they’ll experience sleep inertia—a temporary period of grogginess and mental fog after waking up.
Breus says it’s possible people feel more “awake” if they’re roused during the first or second stage of shallower NREM sleep. Waking up during these shallower sleep stages could decrease sleep inertia and make a person feel more energized during a deprivation period—but Ben Simon says the first half hour can be misleading. She advises people to take stock of their daytime activity levels and emotional responses to see how shortened sleep affects them.
Caffeine
Caffeine blocks a brain chemical called adenosine, which increases sleep pressure, or the biological urge to rest. But the world’s most popular drug has a mean half-life of just five hours before it wears off in the body. Ben Simon emphasizes that caffeine does not get rid of the fatigue caused by sleep deprivation; it simply masks it. “Adenosine is still building up, but the brain doesn’t sense it. So when caffeine wears off, you suddenly get this rush of adenosine—and that’s when you realize how exhausted you are,” she explains.
“Many times, people who believe they can get by without sleep are masking that sleep pressure by ingesting more and more caffeine,” Zeitzer adds. Trying to compensate for this by consuming more caffeine—by chugging multiple cups of coffee or energy drinks, for example—can only help so much: one study found caffeine no longer affected people’s alertness after the fourth day of partial sleep deprivation.
When Adrenaline and Cortisol Wear Off
A single night of shortened sleep might seem harmless, but putting your body under the resulting stress has drawbacks. Losing just two hours of sleep can make people more impulsive and prone to making mistakes. Additionally, the energy from elevated cortisol and adrenaline levels fades over the day. “None of these things will be particularly sustained for a long time,” Zeitzer explains.
And accruing lost hours of sleep can have long-term consequences. Chronically losing sleep increases the risk of several health issues, such as high blood pressure, type 2 diabetes and heart disease. It’s also associated with a decline in cognitive performance.
For a better way to reduce grogginess, Ben Simon advises people to sleep as much as possible for two to three days with no alarm clocks to catch up on rest. Lately, even some high-profile people have seemed to change their mindset when it comes to sleep. Gates, who once claimed sleep was unnecessary, now reportedly rests a minimum of seven hours every night.
The bottom line: You can’t cheat sleep. There is no shortcut to being ready to seize the day—not when sleep is already the greatest life hack. As Ben Simon puts it, “It took Mother Nature millions of years to perfect sleep—to give us optimal performance and mental health.”
