What staying up all night does to your brain | Anna Rothschild

0:04This is Ted Health, a podcast from the Ted Audio Collective, and I'm your host Dr. Shoshana Ungerleiter. Back when I worked the night shift in the hospital, I thought I had mastered the art of running on no sleep. Coffee, adrenaline, and sheer willpower got me through the early hours, but by the morning, my brain felt like it was wrapped in fog. I'd forget simple things, I'd struggle to focus, and let's not even talk about my reaction time driving home. Sleep isn't just about feeling rested. It's a powerful force shaping memory, mood, and even long-term health. This 2024 TED-Ed lesson takes us inside the sleep-deprived brain, revealing what really happens when we push past exhaustion.

0:49Understanding the science of sleep can help us make better choices, not just for staying sharp today, but for protecting our health in the long run. So before trading shut-eye for screen time, you might want to listen to this first. Before we dive in, a quick break to hear from our sponsors.

1:16And now, your TED-Ed lesson of the day. You're just one Roman Empire history final away from a relaxing spring break. But you still have so much to study. So you decide to follow in the footsteps of many students before you and pull an all-nighter. When you stay up all night, you're fighting against your body's natural circadian rhythms. These are the cyclical changes that virtually all living things experience over the course of a 24-hour period, such as sleeping and waking, and they're heavily influenced by light. But for the moment, you're alert and powering through the rule of Julius Caesar.

2:05As the sun sets, your eyes send signals about the dwindling light to a part of your brain called suprachiasmatic nucleus. This is basically your circadian rhythm's clock. It alerts your pineal gland to start producing melatonin. That's the hormone that helps prepare your body for sleep, and levels start to rise about two hours before your normal bedtime. At the same time, neurons in the hypothalamus and brainstem release a compound called GABA. This slows down activity in your brain and can have a calming effect. You're approaching your normal bedtime. Since the brain needs to cool down before sleep, your core body temperature starts to drop.

2:57Huh, that map kind of looks like a face. Uh-oh, your attention has started to drift. Throughout the day, your brain has been releasing a waste product called adenosine. The more adenosine latching onto receptors in your brain, the more tired and inattentive you become. Time for a cup of coffee. Caffeine blocks adenosine from binding to receptors, which can give you a boost of energy. However, it might also make you jittery and increase your anxiety. You're acing these flashcards. Right now, these dates and names are being stored in an area of the brain called the hippocampus. Normally, when you go to sleep, memories like these are consolidated and slotted into long-term storage in your brain's neocortex.

3:48So it's a good thing you only need to remember this information through tomorrow.

3:57Microsleeps are unpredictable periods of sleep that last for only a few seconds and are triggered by sleep deprivation. You stretch in an attempt to stay awake, but at this point your motor skills have also taken a hit. Studies have found that people who have been awake for 19 hours have similar coordination and reaction times as those who have been drinking. As the sun rises, your pineal gland stops releasing melatonin. You feel a second wind come on. And despite everything, you leave for school in a really good mood. Sleep deprivation can briefly induce euphoria. It's caused a temporary boost in dopamine levels, which can, unfortunately, also lead to poor choices.

4:46The final starts off well. It's all multiple choice, but then you get to the essay portion. It's thought that during sleep, our brains process ideas and draw connections between new memories and old ones. So your sleepless brain might be able to regurgitate facts, but you're finding it more difficult to find patterns or problem-solve. You stare at the blank page, defeated. You head up to your room, anxious and irritable. Your amygdala, the part of the brain involved with processing emotion, is going haywire. Your prefrontal cortex usually keeps your amygdala in check, but it still isn't firing on all cylinders.

5:30your bed has never felt so sweet. After one sleepless night, your body and brain bounce back pretty quickly. Which is a good thing, since we can't always control how much sleep we get. But going for long periods without a good night's sleep, or constantly changing your bedtime, can take its toll. Regularly getting less than seven hours of sleep each night is linked to all sorts of health issues from diabetes to stroke to chronic pain. It also leaves you more vulnerable to developing mental health issues like depression. Your sleep schedule can even affect your grades. Studies have shown that college students who keep regular sleep hours have, on average, a higher GPA than students who don't.

6:18So the next time you're thinking of pulling an all-nighter, remember that Rome wasn't built in a day. or, for that matter, one night.

6:35That was TED-Ed.

6:40I will never forget the night I almost fell asleep at the wheel. It was the end of a grueling 30-hour shift during my medical residency. I was exhausted. But I blasted the AC. I rolled down the windows. I turned up the radio. Anything to stay awake. But as I pulled onto the freeway, my eyelids got heavier. My head started to nod. And suddenly, I felt the jolt of my tires hitting the rumble strip. I had drifted into another lane. That moment shook me. I had just spent 30 hours making life or death decisions for critically ill patients. But here I was, putting my own life at risk, simply because I was too sleep deprived to drive safely.

7:33Sleep deprivation doesn't just make you tired. It impairs judgment, it slows reaction time, and can be just as dangerous as driving drunk. Yet in medicine and in so many other professions, pushing through exhaustion is worn like a badge of honor. We praise the all-nighter, the grind, the ability to function on little to no sleep. But what if we've got it all wrong? Let's talk about what sleep deprivation is really doing to us. In 1964, a 17-year-old named Randy Gardner set a world record by staying awake for 264 hours, 11 days, as part of a high school science fair project. Researchers from Stanford University monitored him closely.

8:23At first, he was just tired, but soon he became irritable. He struggled to concentrate and had trouble forming sentences. A few days in, he started hallucinating. By the end, he was paranoid and couldn't remember simple facts. His cognitive and emotional functioning had deteriorated significantly. Afterward, he slept for 14 hours straight and recovered, at least as far as we know. But scientists still don't fully understand the long-term consequences of extreme sleep deprivation. and it raises an important question if this is what happens after just 11 days what kind of damage are we doing to ourselves when we routinely skimp on sleep let's start with the heart if you consistently sleep less than seven hours a night your risk of high blood pressure skyrockets with people sleeping less than four hours having an 86 percent higher risk of it sleep loss also speeds up the buildup of plaque in our arteries, a major predictor of heart attacks and strokes.

9:31And then there's the brain. A long-term study found that sleeping six hours or less per night in middle age increases your risk of dementia by 30%. Why? Because when we sleep, the brain clears out waste products, including the toxins linked to Alzheimer's disease. Without enough sleep, those toxins build up, increasing the risk of cognitive decline. And what about metabolism? If you're trying to lose weight but skimping on sleep, you're making it significantly harder. One study found that people on calorie-restricted diets who slept less than five and a half hours a night lost 55 % less fat, and instead their body started breaking down muscle.

10:16Sleep deprivation also increases cravings for junk food, making it harder to resist unhealthy choices. And let's not forget our emotions and decision-making. Poor sleep makes us more anxious, reactive, and even impulsive. It impairs our ability to weigh risks, making us more likely to engage in reckless behavior. Studies have even shown that sleep-deprived judges hand out harsher sentences the day after losing an hour of sleep due to daylight savings time. Which brings me to one of the biggest unintentional sleep experiments we run every year. According to a study of hospital admissions across Michigan, losing one hour of sleep led to a 24 % increase in heart attacks on the Monday following the switch to daylight savings time in the spring.

11:06And gaining an hour reduced heart attacks by 21 % on the Tuesday following the return to standard time in the fall. Just one hour. Imagine what chronic sleep loss is doing to us over a lifetime. I've actually always been a lover of sleep, but during my medical training, that love had to take a backseat. After enduring the grueling hours of residency, I took a job as a nighttime hospitalist, which meant flipping my schedule entirely. Working through the night while the rest of the world slept, and then trying to get enough rest during the day before doing it all over again. And at first, I didn't think much of it.

11:49I loved the work, the quiet intensity of the hospital at night, the deep focus it required of me, and the way the team came together to handle emergencies without the usual daytime chaos. There was something about the stillness, the hushed tones in the hallways, that made the work feel even more meaningful to me. But over time, I felt the effects. My energy lagged. My mood was unpredictable. My memory just wasn't as sharp. And I found myself feeling foggy, even when I thought I'd slept enough during the day. My body just never fully adjusted. And I struggled with headaches and digestive issues and a persistent feeling of being out of sync.

12:36Even though I love the work, I eventually made the difficult decision to change my schedule. I knew I needed to prioritize my health and well-being, so I transitioned to a daytime role. And the difference was nearly immediate. My energy improved, my focus sharpened, and I felt like myself again. And the research supports what I experienced. Sleep is an investment in better health, a sharper brain, and ultimately a longer life. So here's my challenge to you. Track your sleep for a week. Pay attention to how much rest you're actually getting and how you feel throughout the day. Notice if your energy, your mood, or your focus changes.

13:22Then for the next week, try making sleep a priority and see what happens. Start small. Set a bedtime and stick to it, just like you might do for a child. Cut back on caffeine late in the day and limit screen time before bed to see if that makes a difference. Try a simple wind-down ritual, whether it's reading, stretching, or deep breathing, to signal to your body that it's time to rest. Because the science is clear. Sleep deprivation isn't just making us tired. It's making us sicker, more forgetful, more reactive, and even shortening our lives. And this isn't just about personal exhaustion. Sleep loss affects our society.

14:10It impacts our health systems, our workplaces, and even the safety of our roads. When we treat rest as a luxury instead of a necessity, we all pay the price. The good news? We have the power to change this, not just for ourselves, but for the culture we create. It starts with small choices, one night at a time. Now, go get some sleep.

14:43And that's it for today's episode. Thank you so much for listening. TED Health is part of the TED Audio Collective. This episode was produced by me, Dr. Shoshana Ungerleiter, and Jess Shane. Edited by Alejandra Salazar and fact-checked by Vanessa Garcia-Woodworth. Special thanks to Maria Lages, Farrah DeGrange, Daniela Balarezo, Constanza Gallardo, Tansika Sangmarnivang, and Roxanne Heilash. If you enjoyed today's episode, rate and review the show on your favorite platform. It helps other people to find us. And I'd really love to hear your feedback. Send me a message on Instagram at ShoshanaMD.