Sleep researcher Dr. Jeffrey Iliff answers the internet's burning questions about sleep. What causes sleep paralysis? Can we control our lucid dreams? Why do naps make us more tired? Can you ever catch up on sleep? Dr. Iliff answers all these questions and much more.
JEFFREY ILIFF: Hi, I'm Dr. Jeffrey Iliff, a sleep researcher. Today, we're going to be answering your questions on Twitter. This is shh. This is Sleep Support. @Caddy_Wampus asks, it's 5:00 AM. I can't sleep. I'm eating summer sausage. What is time? What are the circadian rhythms? Well, I don't know why you're eating summer sausage at 5:00 AM. What are circadian rhythms? I can answer that. Circadian rhythm is the drive in your body that entrains all of its functions to the 24-hour light cycle. So there's a part of your brain called the suprachiasmatic nucleus that's the master pacemaker for the circadian rhythm. And what it does is it cues off of the light-dark cycle-- so sunrise and sunset-- to get your brain, and actually the rest of your body, ready to rest at night and ready to act during the day. @rgwill_ rg asks, why do we take naps and wake up more tired? Oh, that's a good question. Because there's good napping and there's bad napping. When you wake up after a nap and you feel like you just got hit by a truck, it's because what has happened is you started to build what's called sleep inertia. So once you start sleeping, after you get past a certain point, your brain gets into the mode that thinks, oh, we're doing this for the next eight hours. And if you interrupt it after it's gotten past that point, it's sort of a rude awakening. And that's why you feel super groggy after a long nap. That's why when you nap, you should actually nap either a very short nap, maybe 20 or 30 minutes, or 90 minutes. So setting an alarm for a 90-minute nap. A 90-minute nap is enough time for you to go through an entire sleep cycle. So going through shallow sleep to deep sleep up to REM, but only once. Not long enough for you to build a lot of sleep inertia, but enough time for you to actually get some of the benefits of sleeping. @Punkassbookjoke says, everybody talking about their weird COVID dreams, and I'm over here like, LOL, what is REM sleep? These are actually EEG caps that measure what's going on inside your brain so that we can see not just whether you're asleep, but what stages of sleep you happen to be in. So rapid eye movement sleep is the phase of sleep connected with dreams. It has a couple of weird features to it. So in one of the things is if we record the electrical activity happening in your brain, it actually looks a lot like an awake brain. In fact, one of the only ways that we can tell that you're in REM sleep and not awake is one of these electrodes here actually connects to the muscles on your face. And so we can actually detect the tension or the absence of tension in your face muscles. And that's how we know you're in REM sleep, not just laying there awake. So during REM sleep, what's happening is your brain is working to consolidate the memories that you form through the course of the day, helping to harden those memories into your long-term memory. Things that are powerful, things that are fearful, things that are scary, things that create anxiety, all of those things are the substance of our dreams. That's part of the way that you encode dreams, is with fear, and pain, and emotion. So it's probably no wonder that we're all having the same weird COVID dream. @rustycovey asks, how will your brain get rid of waste? It isn't sent back into the body to be processed by the organs. How does your sleep play a role in it? This is a really interesting question. It's actually the subject that my lab studies. So your brain is very different from the rest of the body in the way that it manages the waste. So the brain sits in a pool of water called cerebrospinal fluid. And that water helps to cushion the brain from blows that happen. And it actually helps the brain, which has kind of the consistency of room temperature butter. It helps it to not slouch under its own weight. During the daytime, the spaces between the brain cells, which are like the pores of this sponge, are actually pretty small and pretty narrow. So as a result, the water that's outside the brain sort of sits on the outside. But when you go to sleep, the situation completely changes. And the spaces between the brain cells open up, allowing the water that's on the outside of the brain to actually wash into and through the spaces between the brain cells, collecting up the waste that's accumulated through the course of the waking day. And so then this waste-laden fluid, like ammonia that's produced, washes out of the brain out into the fluid around the brain. And then those lymphatic vessels surrounding the brain collect it up and eventually dump it back into the blood. It's like brainwashing but without being in a cult. @Kbgrabham21 asks, have you ever wondered what your brain actually looks like when you sleep? Like, I wonder if my neurons are really just beating the snot out of each other and my dreams are the real reason I'm losing brain cells. I don't think dreams are the reason you're losing brain cells. You can actually see your brain when it's sleeping. You can see it by MRI. Sometimes, you can see it during neurosurgical procedures. The thing about the brain that's really striking is the way that it pulsates. So the brain is just this big pulsating mass of tissue and blood. So you see it pulsating with the heart rate. And you see it pulsating and swelling with the respiratory cycle. And there's actually these even low frequency oscillations that happen as blood vessels in the brain dilate and contract. Those pulsations are actually part of the process driving the clearance of waste into and out of the brain. @fxmish asks, does anyone that can lucid dream having any tips on how to do it? So lucid dreaming, think the movie "Inception," is being aware of the fact that you're dreaming when you are so that you can control what's happening around you. It's a little fringy, but there's actually a little bit of research on the subject. So there's some data that suggests that you can use transcranial electrical stimulation. So stimulating your brain with electricity at certain frequencies can increase the likelihood that a person who normally can't lucid dream actually can be able to. There's also some approaches in sleeping itself that seems to increase people's ability to lucid dream. You set an alarm for five hours after you go to sleep and then wake up. Right after you wake up, you think to yourself, I'm going to be dreaming, I want to wake up during my dream. Repeat that to yourself again and again and again as you go back to sleep. Your chances of being able to know that you're in a dream when you go back into sleep actually increase between 100% to 1,000%. So it may be either through stimulation or maybe through some cognitive tricks you can actually increase your chances of being able to lucid dream. @karamel_cookie asks, so is, like, sleepwalking a real thing? Yes, sleepwalking is a real thing. So sleepwalking is more common in kids and in adolescents. It tends to disappear as people move through adolescence into adulthood. The interesting thing about sleep sleepwalking is that your brain is asleep and yet you can accomplish very complicated tasks. So when you're sleeping, your brain is supposed to be a little bit disconnected from your awareness. And it's supposed to be disconnected from how your body moves. Sometimes, those connections, they can get opened or they can get closed at the wrong time. So you see things like sleep talking or sleep moaning. You see people who have something called REM sleep behavior disorder, which is where you actually act out the things that are happening in your dreams, sometimes even violently, sometimes injuring your bed partner. So there's a bunch of different types of things, some of them interesting, some of them a little scary, that can happen when the processes governing sleep and your body become misaligned. @swankpharm asks, how many types of sleep do we have? You actually see that your brain is doing a couple of distinct things through the course of the night. One side of that is called REM sleep, or rapid eye movement sleep, and that's the part of sleep that's most associated with dreaming. There's also non-REM sleep. Non-REM sleep sort of breaks into three different categories. There's N1, N2, and N3. N1 is the shallowest type of sleep. So that's maybe the first 10 minutes after you first fall asleep. And that's the time when you're sort of most awake. It's easy to sort of pop back up awake. N2 sleep is sort of the mid layer on your way to deep sleep. During that phase, you're a little deeper in. And your body starts to actually do some funny things. So that's when sometimes people will twitch and move a little bit during N2 sleep. The deepest sleep is called N3 sleep or slow wave sleep. And during that time, if we record what's happening in your brain, your brain is actually oscillating between states where everything's on and everything's off. And it's doing those oscillations about one every second. Those are called slow oscillations. That slow wave sleep is the deepest part of sleep. And then you'll come back up into REM sleep, where you'll typically do dreaming. One of those cycles is about 90 minutes or so. During the course of the night, you go through several of those cycles, maybe three or five of them. Later on into the night, there's less slow wave sleep and more REM, which is one of the reasons why maybe we remember the dreams that we're having late in the night better. @moniajar asks, what is sleep apnea? I would have asked Google, but I prefer a more simple answer. Sleep apnea is a condition where you stop breathing several times through the course of the night. So it can actually be a physical obstruction to your airway that keeps you from sleeping. Regardless of the cause, the result's bad. Your brain is incredibly active. So the neurons in your brain are firing trillions and trillions of times a second. And all of that activity takes a huge amount of oxygen and glucose and energy to keep it going. And every time you stop breathing during the night, you're depriving your brain for just a little while of the energy that it needs and of the oxygen that it needs. And it isn't until your brain is screaming for more oxygen that you actually gasp yourself awake. And as you add that up over the course of many nights over weeks and months and years, the added stress that that puts on not just your brain, but actually your whole body, can increase your risk of cardiovascular disease like heart attacks and strokes, diabetes. The good news is that sleep apnea, much of it, is actually pretty treatable with an approach called CPAP, which is basically just a mask that goes over your face. And it uses a little pump to sort of force air in and out. And the forcing of that air in and out of your lungs helps to keep your airway open and keep you from stopping breathing during the night. The bad news is many more of us actually have sleep apnea than know it. What does it look like? How do I know if I have sleep apnea? Well, common symptoms include heavy snoring, waking up gasping. If that sounds like you, it might be worth getting checked out with your physician. @ThayliaClara asks, what causes insomnia? Because I literally cannot go to sleep at a decent time, no matter how tired I am. Upside down smiley, upside down smiley, upside down smiley. Well, insomnia is pretty common. So it's not being able to either go to sleep or it's not being able to stay asleep once you are asleep. There are genetic causes of insomnia. Sleep apnea can cause insomnia. But, frequently, it's the stress in our lives that can cause either acute insomnia, which is insomnia that just happens every so often, or chronic insomnia that happens all the time. So things that are important for sleep hygiene include going to sleep at the same time every day and waking up at the same time every day so that your body can entrain to a certain rhythm that can become predictable. It's staying off the screens for an hour before you go to bed. It's sleeping in a cool, dark room where that isn't also your office so that you can sort of focus in on the process of either having sex or going to sleep, which is really the only two things you should be doing in your bedroom. @Mash_Selaelo asks, what causes sleep paralysis? Had it twice last night. Scream emoji. That sounds like kind of a rough night. Sleep paralysis is when you're laying in bed. You're sort of coming out of sleep. Or sometimes it's when you're going into sleep. You're aware of your environment around you. Perceive what's happening. But you can't move the rest of your body. You're sort of paralyzed. And sometimes it can be accompanied by visual or auditory hallucinations, or feelings of fear or terror, or even feelings of suffocation. So it can be completely terrifying. Your body has a couple of disconnect switches that it throws so that all the activity happening in your brain while you're dreaming or during your REM sleep doesn't cause you to act out your actions in the world around you. In sleep paralysis, those disconnect switches seem to get a little jumbled up so that the switch that disconnects you from awareness of your environment sort of gets opened so you become aware even while the switch disconnecting you from your body is still closed. If we do an EEG study in people who are having sleep paralysis episodes, we actually see that they still seem to be in REM sleep. So even though while you're aware of what's around you, your brain is still dreaming, and your body still thinks you're asleep. It's just that you're stuck feeling awake. @YaTuSabesWho asks, how do sleeping pills work? It depends a little bit on the sleeping pills that you're talking about. So let's start with the simpler ones. So a lot of people take melatonin to help them sleep. Melatonin is actually a naturally occurring molecule in your body that is part of how the body induces drowsiness. It's actually a part of the circadian sleep drive to help sort of prime the brain to get ready to sleep. Other commonly used sleep medications include drugs called sedative hypnotics like Ambien, which is a commonly used one, and also benzodiazepines, which are sort of anti-anxiety medications that can be used sometimes to help with sleep. Those drugs are very powerful drugs. They're available only by prescription. They have the potential for forming addiction and for habit forming. So they need to be used under the supervision of a physician. They work by targeting a neurotransmitter system in the brain which dampens down neural activity and to reduce arousal in the brain to help you sleep. Many of those sleep medications don't produce the same type of natural cycling of sleep that your brain wants. So if you suffer from an insomnia or if you have other sleep issues, other approaches like improving your sleep habits or even cognitive behavioral therapy can be actually more helpful in helping your brain to sleep naturally than trying to accomplish that with the drug. @TalyaGalasko asks, is it really true that you can never catch up on sleep? If yes, I'm actually so fucked. Well, you kind of are. The sleep that you lose is sort of gone forever. And many of the benefits of that sleep, whether that's memory consolidation or whether that's the rejuvenation that happens in the brain, you sort of missed the boat. But there is something that builds up the longer you're asleep and the less sleep that you get that's called sleep debt. And what sleep debt is is the drive to sleep more that builds through the course of the day, and it builds with sleep restriction. And so when you go to sleep, that sleep debt is relieved and sort of paid off. So there is a sense in which you can catch up on sleep. An interesting study that was measuring waste clearance out of the brain showed that if a person was kept up all night, the slowing of brain clearance that happens in a person who stays up all night, actually, it took seven days for it to catch up. So even the second day after the sleep deprivation it hadn't even caught up. So you don't necessarily catch up on lost sleep within a day or two. It may take much longer. @FurlingBird asks, how long does coffee affect your sleep system? The answer is that it's longer than most people think. So the active ingredient in coffee is caffeine, which targets a receptor in the brain that helps to turn off neurons. So by blocking that receptor, it turns on neurons. That's how coffee has its main effect on you being awake. Now, the half life of coffee in the blood is between 4 and 6 hours, which means it takes the better part of half a day for it to clear out of your body. So if you want to not have caffeine influencing your sleep when you go to bed, you probably need to be stopping drinking caffeinated coffee or other drinks like Monster or these other energy drinks by around 2:00 or 3:00 in the afternoon. One of the things that caffeine does is it sort of keeps your brain aroused. It keeps your brain awake. Maybe not all the way awake. So you might be skimming through the shallow phases of sleep and not getting into those really deep phases of sleep that are necessary for brain health. @lindsay_chat asks, would love to get your tips on how to handle jet lag? What do you find effective? One approach is ahead of your trip, if you can do this, if your schedule allows you, you can start moving your sleep wake cycle back an hour a day so that by the time you leave, you're within an hour or two of your target time zone. So if you're going to Europe and it's a six hour difference, six days ahead start moving your time to go to sleep ahead one hour, one hour, one hour so that by the time you leave, you're going to bed at 6:00 PM. But the good news is by the time you get into Europe, jet lag will be smaller. @thatjuanpablo how do you track your sleep? Of course, most of us don't have EEG systems in your house unless you're some kind of weirdo. So most of us use an approach called actigraphy to measure our sleep. And so that's like your Apple Watch or a Fitbit. And what that does is it's measuring your movement and inferring from your motion. It's good at detecting when you're in bed, when you're asleep. It's not as good as the detecting what kind of sleep you're in. So when your Apple Watch tells you or your Fitbit tells you, well, I had this much deep sleep, maybe you did. Maybe you didn't. But in terms of knowing how much sleep you're getting, which is probably the more important thing, it's actually pretty good for that. @bicky84 asks, ran on four hours of sleep. Going to sleep to wake up in two hours. Are there negative effects of lack of sleep? Was that a dancing bear? It probably wasn't a dancing bear. That was probably the visual hallucinations from you not sleeping enough. The human brain needs seven to nine hours of sleep for adults. Kids need more. Teenagers, they seem to need a lot more. If you don't get enough sleep, if you go at night without sleep, we can actually measure deficits in your memory, in your attention, in your processing and response speed, and in your decision making. So your lack of sleep, you know that it affects how you feel today and tomorrow. But there's emerging data that suggests that long term lack of sleep or long term poor sleep may actually be setting the stage for chronic diseases like diabetes or heart disease or even cancers. Some pretty recent data suggests that, actually, poor sleep, especially in midlife, may be setting the stage for risk for developing dementia later on in life in your 60s, 70s, and 80s. So how you treat your brain today may be influencing the mind that you get to have in 20 or 30 years. @LastMoonicorn asks, if dreams are your brain trying to sort out memories and information while you sleep or work through general data, what is my brain doing? Why is it creating places I totally forget when I wake up, but in my dreams, it's like I have my own separate memory? So all of us have these uncanny dreams that are weird mismatches of beluga whales, Disneyland vacations, and our mother-in-law. So what's going on there? One of the things that the brain might be doing is it's actually using our memories, putting them together to try to generate new insights and that maybe it's that novel recombination process is where human creativity and maybe even human inspiration comes from. In terms of why you don't remember it, maybe it's a little bit like your laptop, the way that it does disk maintenance during the night. So while it's doing its fragmentation, the screen's off. The keys aren't lit. But it's because that's something that's for the computer. It's not for you, the user. It's not for the outside world. @anamnesis80 says, you know what bugs me? Why do we need to sleep? I mean, I know the biology behind it. But why? What's the purpose of sleep? Well, first, I have to say that you probably don't know the biology behind sleep if you're asking this question. But you shouldn't feel bad because the reality is we really don't understand completely why it is that we sleep. We have some hints. So at a cellular level, though, we see that some interesting things are happening. So the brain is made up of trillions of connections between all the nerve cells. Those connections are your motions. They're your thoughts. They're your memories. And you're making new connections constantly. But some of those connections are important. The connections like, how do I get away from a saber tooth tiger? But some of those are less important, like the 19th cat video that you watched on YouTube last night. And so if your brain kept all the connections every single day, it would become this clogged up rat's nest of information and connections so you'd never be able to think your way through anything. So during sleep, connections that are important, the ones that are connected to emotions or that are powerful, those actually firm up. And the ones that are less important, the weak ones actually get trimmed away. There's actually cells in your brain that eat the extra connections while you're asleep. And so if you don't sleep, those processes of firming up and of pruning don't get to happen, which is why we think it has such an important role in memory. All right. So those are all the questions for today. There were some really awesome ones out there. The big takeaway is your brain needs sleep to be healthy. And it wants to sleep. Our job as sleepers is to try to get out of the way, try to set the stage for it to do the thing that it wants to do. Thank you for watching Sleep Support.