Summary from Professor Matthew Walker

– 2 stages which are REM (Rapid Eye Movement) and Non-REM. REM is also known as dream sleep. Non-REM is divided into 4 stages. The deep stages 3 and 4 is where body replenishment, cardio, metabolism, etc happens. Your body resists going into these stages when they’re in a foreign environment like hotels as a threat detection system.

– Not always about quantity it’s also quality but both matter regularly.

– If you have been drinking or getting high every night which suppresses heavy REM sleep. So your body builds up a clock counter of how much REM sleep you should be getting. The appetite increases. So you get a REM sleep rebound effect when you don’t have crap in your system. Intense dream sleep session happen. After about 6 hours the body takes care of the alcohol so the last 2 hours of your sleep will have these intense dreams.

– Weed helps people put people to sleep. Alcohol is a sedative so it doesn’t really help sleep. Weed blocks the REM sleep.

– Delirium tremens is like when the REM sleep has been building up for so long, as in alcoholics, that it starts spilling over into wakefulness. It starts taking it while one is awake. How necessary does sleep have to be that it takes over like that.

– Men who sleep 5-6 hours a night will have testosterone levels of someone 10 years their senior. Lack of sleep ages you.

– Talks about people who sleep for a minute and the effect of delusion and hallucination they get are similar to what happens to us in the sleep cycle. Confusion of time, place, etc. Amnesia, etc. All this happens in our sleep. In REM sleep some parts of the brain activate 30% more. Visual, motor, emotional and memory parts of the brain increase. The prefrontal cortex (CEO of the brain) switches off. So the prison guard basically goes to sleep or there is no driver.

– One theory of dreaming is that it tries to make sense of the world and package it accordingly. Another theory is about accessibility vs. availability of remembering the dream. We forget the dream but then see something random and it’s like we found the IP address to the memory of the dream. Non-conscious memory processing so it’s all available when we have access to the right IP. (No solid science on this though)

– Noradrenaline (distress chemical) gets shut off in dream sleep. When you wake up you have a spike in it. Acetylcholine (a nootropic which enhances the brain) does the opposite. So the brain is pushing out the memory or information.

– Different theories of dreams. Important point is that calories are so precious to the body that they the body can’t just sacrifice them and dreaming requires calories.

– Rogan trying to defend weed smoking. All stages of sleep are important. Mother nature would not waste time to put you through it all. During sleep your brain paralyses your body. This way you don’t kick and kill people while reacting in sleep.

– When they studied rats the measured the brain activity and it made music to patters say like running in a maze. So the music sequence is the same in sleep but 20 times faster. The brain is replaying and improving. Practice with a night of sleep makes perfect. Sleep is the best and legal performance enhancement.

Everyone should get 7 to 9 hours sleep

– Less than 7 hours and ‘objective impermance’ can be measured in the brain and body. Paras note: No idea what that is, googled it an some other stuff came up.

– The less you sleep: Lactic acid builds up quicker. Optimal lung function decreases. Your peak muscle strength, jumping height and running speed are compromised. Injury risk increases (5hours vs. 9hours has a 60% increase in risk!). Stability muscles start failing, which seems small but are so crucial.

– Practicing things mentally as sportsmen do is 50% as important as the real thing. It changes connections in the brain. Passive play, visualisation are so important. The brain does things automatically after some practice like driving, playing instrument, etc. The brain chunks it down. Sleep is where the brain fixes the broken bits. The is why people say ‘sleep on it’. Benefits of dreaming is that the brain seeks out and tests connections. The periodic table was figured out like this. So many cultures have these maxims on sleep.

– Edison used naps for this with paper and pen. He put an upside down saucepan under his hand where he’d hold 2 steel balls. So he never went into full sleep and soon as the balls crashed on the pan he’s start writing down his idea. Even though Edison gave us lack of darkness which bothers our sleep. Lightbulbs suppress melatonin which tells the brain, plus screen usage.

– One hour of screen reading delays melatonin 3 hours as opposed to book reading. You don’t get the same amount of REM sleep and the next day you don’t feel as refreshed. You can take melatonin when you’re changing timezones while travelling but it doesn’t seem to work in the same timezone. At the same time don’t stop taking it if you think it’s helping as the placebo effect is the most reliable effect in all of pharmacology. It is more useful for older people who’s body clock has faded than for young people.

– Strategies to get better sleep
1 – Regularity,
2 – Light, switch off half the lights before bed and reduce the rest,
3 – Keep it cool, your brain needs cooler temperatures, faster and deeper non-REM sleep. Heating your hands and feet will help cool them faster so have a hot bath. The vasodilation brings the heat out of the body. So there is a massive dump of heat and your core body temperature plummets. That’s what makes you sleep so much easier. Light and temperature triggers sleep.
4 – Don’t go to bed too full or too hungry.

– Midnight means middle of the night so that should be our half way point of sleep.

– We may also be designed to sleep biphasically. So have 2 sleeps. (Paras note: Gujarati’s call this baporyu, Spanish call it siesta). Studies show that there is a drop in alertness between 2 to 4pm and it’s not related to diet.

The shorter your sleep, the shorter your life

– Yes you’ll sleep when you’re dead because you’ll die sooner.

– Wakefulness creates low level brain damage. So just being awake now you’re getting brain damage. Your sleep repairs that. Insufficient sleep will increase your likelihood of developing Alzheimer’s.

– Shift workers have higher rates of obesity, diabetes, cancer. Lake of sleep is linked to cancer of the bowel, prostate, breast. The world health organisation has classed any type of shift work as a carcinogen.

– 2 hormones the control your appetite and weight. Leptin and Ghrelin. Leptin tells your brain that you’re full, you’re satiated and you don’t want to eat anymore. Ghrelin does the opposite. Lack of sleep decreases leptin and increases ghrelin. People sleeping less eat 200-300 extra calories EACH DAY! 70,000 extra calories a year! And it’s not only that you eat more, you eat more of the wrong things. Plot sleep and obesity on a graph and they both co-relate.

– Prophylactic napping: Strategically helping combat your lack of sleep. You just can’t keep using naps to catch up on missed sleep. You don’t fully recover all the lost sleep. There is no credit system.

Human beings are the only animal on the planet that deprive themselves of sleep for no apparent reason

– Mother nature hasn’t experience this or is not designed to defend this which is why we have so many issues. The only time this happens in nature is when there is extreme starvation and the animal has to stay awake to forage in a larger circumference. This is why people have such bad sleep while fasting.

– Chemical pathways seem to be beneficial while fasting. But fasting over 3-4 days starts bothering sleep. There is room for fasting especially as studies have shown it helps the anti-ageing process. Fasting releases the ghrelin that is forcing you to go hunt and gather.

– Weeks studies of 7, 5, 3 hours of sleep show that within a week of less than 6 hours of sleep your cognitive performance nosedives.

After 20 hours of being awake, you are as impaired as if you were drunk

– Every 30 seconds there is a car accident linked to sleeplessness. Drowsy driving kills more people than alcohol or drugs combined. This is because when you are under-slept you have micro-sleeps. Eyes partially close but your brain goes to sleep for a brief period.

– School times were shifted from 7:35 to 8:55am and that caused a 70% reduction in car crashes. Another study showed a 212 point increase in SAT scores just by changing the time to one hour later again.

– Almost 1 out of 2 American’s are not getting enough sleep. The average went from 7.9 hours to 6.5 hours.

– You don’t know when you’re sleep deprived. Just how drunks think they are good to drive when they’re not.

– Better sleep makes you more productive. Less sleep means taking fewer work challenges. Taking simple tasks. Fewer creative solutions to challenges. Slack off (social loafing) and ride the coat tails of other peoples hard work. The less sleep the CEO has the more the employees will rate the CEO as less charismatic. Less efficiency.

– Creative writers will play video games till 2am then start writing. Theory of how the prefrontal cortex/logical brain switching off to get the creative, out of the box kind of writing.

– Even if you have 8 hours sleep for most nights a week and just 2 hours one of the nights it’s still going to reduce the 70% of the anti-cancer fighting cells.

– Daylight savings! Happens to millions where they lose 1 hour. There is a 24% increase in heart attacks. And when the millions get back that 1 hour there is a 24% decrease in heart attacks.

– Insufficient sleep will erode your very fabric of life… your DNA code. 711 genes were distorted just by one week of 6 hours sleep. So either the good ones that protect you were switched off or the ones that cause tumours and bad things were switched on.

– As your grow older your body-clock moves forward so you sleep later and wake up later.

THE MINIMUM SLEEP YOU SHOULD GET IS 7 HOURS!

– There is a rare gene that people can survive 5 hours of sleep and be ok. But the gene is so rare that you are more likely to be struck by lightening.

– So when you sleep there is a sewage system that cleanses out the metabolic system in high gear. The chemical that contributes to Alzheimer’s builds up with lack of sleep instead of getting flushed out.

– Caffeine does help keep going when your alertness starts dropping. Dopamine helps as you get an increase in alertness.

– Some kids diagnosed with ADHD are just sleep deprived or have some sleep disorder breathing. ADHD disappears when the tonsils are treated or sleep disorder is handled. Other the other hand ADHD kids are given a chemical that is a stimulant which doesn’t help when they’re already sleep deprived or have a hard time sleeping.

– Also sleeping pills are associated with risk of death, cancer, etc.

– Doctors have only 2 hours worth of sleep education. Basically this podcasts worth of education. The medical industry itself has issues because the junior residence working 30hour shifts have 416 (or 460)% more likely to make diagnostic errors. 170% increased risk of major surgical error with sleep less than 6 hours. 168% increased risk of car accident when they finish their shift ending up back in the same room they were in only as a patient this time.

– History of why residence did this and William Halsted who was studying cocaine was a cocaine addict and then the guy challenged fellow residence to compete matching his endurance. He checked himself in to recover from cocaine and ended up coming out being a cocaine and morphine addict. He also used to get his shirts starched and with other ‘white chemicals’. So the horrendous practice of staying awake this long was because of him.

– So 1 in 5 residence will make a serious error because of this shift. 1 in 20 will kill a patient because of a fatigue related error. And there are over 20,000 residents.

– Hospitals could have patience out sooner if they regulated the bright lights accordingly. A significant number of ICU alarms are false alarms because of lack of sleep from patients too. Infants had so many health benefits with regulated lights. They got out 5 weeks earlier! Flights that use earplugs and face masks would help get better sleep. The hospital form should have a section for patient’s natural sleeping tendencies to try and accommodate for it.

Sleep is the elixir or life. It is the most widely available, democratic, powerful health care system imaginable.

– If you are dieting but not getting sleep. 70% of the weight loss will be from lean body mass instead of fat. Your body becomes stingy giving up fat with it’s sleep deprived.

– Lack of sleep cost counties 2% of their GDP ($411,000,000,000 in America). If that was fixed you could double investment in education, you could half the cost of health care.

– Seasonal Affective Disorder (SAD) or the winter blues. Best is to use melatonin at the right times and use a light box when you need to fake daylight. Also Vitamin D supplementation is good.

Why Sleep is More Important Than Diet | Shawn Stevenson on Health Theory

Summary (Only includes sleep topics as it really starts from 22 mins and ends at 44 mins in the video):
– Money time sleep is between 10pm and 2am when melatonin is best released. Melatonin helps you go through sleep cycles more efficiently and all cycles are important. You produce more growth hormone then, which is muscle sparing.

– Thermoregulation. Body temps go down when you sleep. People who are too hot will not sleep good. Then the body naturally heats up as you get closer to waking up.

– 8.5 hours of sleep vs. 5.5 hours of sleep there was a 55% more body fat lost with longer sleep. Your body needs darkness to sleep.

– Leptin. See above summary. Just one night of sleep depravation makes you hungry for the wrong things.

– Cortisol. It’s not really a bad guy because it’s good for the thyroid. But one night of sleep depravation drastically increases levels and suppresses melatonin production. It will bread down your muscle tissue as a flight of fight response.

Optimise sleep by:
– Changing time you exercise. Best time to exercise is morning. 25% better blood pressure. 20 seconds of exercise with 10 seconds of rest and repeat for 4 minutes. Cortisol reset.

– Blue light exposure from devices suppresses melatonin. Every hour on screen suppresses melatonin for 30 mins. There is a great connection between sex and sleep. Better than instagram.

– Create an eating ritual.

– Turn down temp to 62f (16c) – 88f (20c). Bedroom should be for bed only, no TV etc. Double S – sleep and sex. People with a TV in the room have a lot less sex.

– Biological night and a dark environment. Street lights etc can have an impact on your sleep. Skin also has photoreceptors. Be mindful of bulb colours.

Summary from Science of Sleep – National Geographic

While We Sleep, Our Mind Goes on an Amazing Journey
Our floodlit society has made sleep deprivation a lifestyle. But we know more than ever about how we rest—and how it keeps us healthy.

Nearly every night of our lives, we undergo a startling metamorphosis. Our brain profoundly alters its behavior and purpose, dimming our consciousness. For a while, we become almost entirely paralyzed. We can’t even shiver. Our eyes, however, periodically dart about behind closed lids as if seeing, and the tiny muscles in our middle ear, even in silence, move as though hearing. We are sexually stimulated, men and women both, repeatedly. We sometimes believe we can fly. We approach the frontiers of death. We sleep.

Everything we’ve learned about sleep has emphasized its importance to our mental and physical health. Our sleep-wake pattern is a central feature of human biology—an adaptation to life on a spinning planet. When this circadian rhythm breaks down, recent research has shown, we are at increased risk for illnesses such as diabetes, heart disease, and dementia.

Light rich in blue wavelengths promotes alertness and is good in daytime, Lockley says. Redder light is best at night because it has less power to alert the brain or reset the biological clock.

The average American today sleeps about two hours less than a century ago. Due to electric lights, televisions, computers, and smartphones. A full night’s sleep now feels as rare and old-fashioned as a handwritten letter.

Light at night inhibits the production of melatonin, the hormone that helps regulate our daily biological rhythms.

Stages 1-2
As we fall into sleep, our brain stays active and fires into its editing process—deciding which memories to keep and which ones to toss.

The initial transformation happens quickly. The human body does not like to stall between states, lingering in doorways. We prefer to be in one realm or another, awake or asleep. If our circadian rhythm is pegged to the flow of daylight and dark, and if the pineal gland at the base of our brain is pumping melatonin, signaling it’s nighttime, and if an array of other systems align, our neurons swiftly fall into step.

When we’re fully awake, neurons form a jostling crowd, a cellular lightning storm. When they fire evenly and rhythmically, expressed on an electroencephalogram, or EEG, by neat rippled lines, it indicates that the brain has turned inward, away from the chaos of waking life. At the same time, our sensory receptors are muffled, and soon we’re asleep.

Scientists call this stage 1, the shallow end of sleep. It lasts maybe five minutes. Then, ascending from deep in the brain, comes a series of electric sparks that zap our cerebral cortex, the pleated gray matter covering the outer layer of the brain, home of language and consciousness. These half-second bursts, called spindles, indicate that we’ve entered stage 2.

Our brains are just differently active. Spindles stimulate the cortex in such a way as to preserve recently acquired information—and perhaps also to link it to established knowledge in long-term memory. In sleep labs, when people have been introduced to certain new tasks, mental or physical, their spindle frequency increases that night. The more spindles they have, it seems, the better they perform the task the next day.

The strength of one’s nightly spindles might even be a predictor of general intelligence. Sleep literally makes connections you might never have consciously formed, an idea we’ve all intuitively realized. No one says, “I’m going to eat on a problem.” We always sleep on it.

The Japanese term inemuri, or “sleeping while present,” is a distinct form of napping in which a person dozes in a place not meant for sleep, such as the subway—or even at a dinner party or the office. Since you’re officially not sleeping, to be socially acceptable you should behave as is appropriate in a certain situation. For example in a meeting, you half pretend to be listening or hide your sleeping head behind paperwork. If you’re not already known as a slacker, a little inemuri may even enhance your business reputation: It demonstrates that you’re working yourself to exhaustion.

The waking brain is optimized for collecting external stimuli, the sleeping brain for consolidating the information that’s been collected. At night, that is, we switch from recording to editing, a change that can be measured on the molecular scale. We’re not just rotely filing our thoughts—the sleeping brain actively curates which memories to keep and which to toss.

It doesn’t necessarily choose wisely. Sleep reinforces our memory so powerfully—not just in stage 2, where we spend about half our sleeping time, but throughout the looping voyage of the night—that it might be best, for example, if exhausted soldiers returning from harrowing missions did not go directly to bed. To forestall post-traumatic stress disorder, the soldiers should remain awake for six to eight hours, according to neuroscientist Gina Poe at the University of California, Los Angeles. Research by her and others suggests that sleeping soon after a major event, before some of the ordeal is mentally resolved, is more likely to turn the experience into long-term memories.

Stage 2 can last up to 50 minutes during the night’s first 90-minute sleep cycle. (It typically occupies a smaller portion of subsequent cycles.) Spindles can arrive every few seconds for a while, but when these eruptions taper off, our heart rate slows. Our core temperature drops. Any remaining awareness of the external environment disappears. We commence the long dive into stages 3 and 4, the deep parts of sleep.

Stages 3-4
We enter a deep, coma-like sleep that is as essential to our brain as food is to our body. It’s a time for physiological housekeeping—not for dreaming.

Every animal, without exception, exhibits at least a primitive form of sleep. Three-toed sloths snooze about 10 hours a day, a disappointing display of languor, but some fruit bats manage 15 hours, and little brown bats have been reported to laze for 20. Giraffes sleep less than five. Horses typically sleep part of the night standing up and part lying down. Dolphins sleep one hemisphere at a time—half the brain sleeps while the other half is awake, allowing them to swim continuously. Great frigate-birds can nap while gliding, and other birds may do the same. Nurse sharks rest in a pile on the ocean floor. Cockroaches lower their antennae while napping, and they’re also sensitive to caffeine.

Sleep, defined as a behaviour marked by diminished responsiveness and reduced mobility that is easily disrupted (unlike hibernation or coma), exists in creatures without brains at all. Jellyfish sleep, the pulsing action of their bodies noticeably slowing, and one-celled organisms such as plankton and yeast display clear cycles of activity and rest. This implies that sleep is ancient and that its original and universal function is not about organising memories or promoting learning but more about the preservation of life itself. It’s evidently natural law that a creature, no matter the size, cannot go full throttle 24 hours a day.

New memories are consolidated during sleep

For humans this happens chiefly during deep sleep, stages 3 and 4, which differ in the percentage of brain activity that’s composed of big, rolling delta waves, as measured on an EEG. In stage 3, delta waves are present less than half the time; in stage 4, more than half. (Some scientists consider the two to be a single deep-sleep stage.) It’s in deep sleep that our cells produce most growth hormone, which is needed throughout life to service bones and muscles.

There is further evidence that sleep is essential for maintaining a healthy immune system, body temperature, and blood pressure. Without enough of it, we can’t regulate our moods well or recover swiftly from injuries. Sleep may be more essential to us than food; animals will die of sleep deprivation before starvation, says Steven Lockley of Brigham and Women’s Hospital in Boston.

Good sleep likely also reduces one’s risk of developing dementia. A study done in mice suggests that while we’re awake, our neurons are packed tightly together, but when we’re asleep, some brain cells deflate by 60 percent, widening the spaces between them. These intercellular spaces are dumping grounds for the cells’ metabolic waste—notably a substance called beta-amyloid, which disrupts communication between neurons and is closely linked to Alzheimer’s. Only during sleep can spinal fluid slosh like detergent through these broader hallways of our brain, washing beta-amyloid away.

Sleep is crucial for childhood health and development; it’s when most growth hormone and infection-fighting proteins are released. Poor sleep in kids has been linked to diabetes, obesity, and learning disabilities.

While all this housekeeping and repair occurs, our muscles are fully relaxed. Mental activity is minimal: Stage 4 waves are similar to patterns produced by coma patients. We do not typically dream during stage 4; we may not even be able to feel pain. In Greek mythology the gods Hypnos (sleep) and Thanatos (death) are twin brothers. The Greeks may have been right.

“You’re talking about a level of brain deactivation that is really rather intense,” says Michael Perlis, the director of the Behavioral Sleep Medicine program at the University of Pennsylvania. “Stage 4 sleep is not far removed from coma or brain death. While recuperative and restorative, it’s not something you’d want to overdose on.”

At most, we can remain in stage 4 for only about 30 minutes before the brain kicks itself out. (In sleepwalkers at least, that shift can be accompanied by a bodily jerk.) We often sail straight through stages 3, 2, and 1 into awakeness.

Even healthy sleepers wake several times a night, though most don’t notice. We drop back to sleep in a matter of seconds. But at this point, rather than repeating the stages again, the brain resets itself for something entirely new—a trip into the truly bizarre.

According to the U.S. Centers for Disease Control and Prevention, more than 80 million American adults are chronically sleep deprived, meaning they sleep less than the recommended minimum of seven hours a night. Fatigue contributes to more than a million auto accidents each year, as well as to a significant number of medical errors. Even small adjustments in sleep can be problematic. The Monday after a daylight saving time change in the U.S., there’s a 24 percent increase in heart attacks, compared with other Mondays, and a jump in fatal car crashes too.

During our lifetimes, about a third of us will suffer from at least one diagnosable sleep disorder. They range from chronic insomnia to sleep apnea to restless leg syndrome to much rarer and stranger conditions.

In exploding head syndrome, booming sounds seem to reverberate in your brain as you try to sleep. A Harvard study found that sleep paralysis—the inability to move for a few minutes after you’ve woken from dreaming—is the genesis of many alien abduction stories. People with Kleine-Levin syndrome will, every few years, sleep nearly nonstop for a week or two. They return to regular cycles of consciousness without any discernible side effects.

Insomnia is by far the most common problem, the main reason 4 percent of U.S. adults take sleeping pills in any given month. Insomniacs generally take longer to fall asleep, wake up for prolonged periods during the night, or both. If sleep is such a ubiquitous natural phenomenon, refined across the eons, you might wonder, why do so many of us have such trouble with it? Blame evolution; blame the modern world. Or blame the mismatch between the two.

Evolution endowed us, like other creatures, with sleep that is malleable in its timing and readily interruptible, so it can be subordinated to higher priorities. The brain has an override system, operating in all stages of sleep, that can rouse us when it perceives an emergency—the cry of a child, say, or the footfall of an approaching predator.

The problem is that in the modern world, our ancient, innate wake-up call is constantly triggered by non–life-threatening situations, like anxiety before an exam, worries about finances, or every car alarm in the neighborhood. Before the industrial revolution, which brought us alarm clocks and fixed work schedules, we could often counteract insomnia simply by sleeping in. No longer. And if you’re one of those people who are proud of being able to fall asleep quickly just about anywhere, you can stop gloating—it’s a distinct sign, especially if you’re less than 40 years old, that you’re acutely sleep deprived.

The first segment of the brain that begins to fizzle when we don’t get enough sleep is the prefrontal cortex, the cradle of decision-making and problem-solving. Underslept people are more irritable, moody, and irrational. “Every cognitive function to some extent seems to be affected by sleep loss,” says Chiara Cirelli, a neuroscientist at the Wisconsin Institute for Sleep and Consciousness. Sleep-deprived suspects held by the police, it’s been shown, will confess to anything in exchange for rest.

Anyone who regularly sleeps less than six hours a night has an elevated risk of depression, psychosis, and stroke. Lack of sleep is also directly tied to obesity: Without enough sleep, the stomach and other organs overproduce ghrelin, the hunger hormone, causing us to eat more than we need. Proving a cause-and-effect relationship in these cases is challenging, because you can’t subject humans to the necessary experiments. But it’s clear that sleeplessness undermines the whole body.

Power naps don’t solve the problem; nor do pharmaceuticals. “Sleep is not monolithic,” says Jeffrey Ellenbogen, a sleep scientist at Johns Hopkins University who directs the Sound Sleep Project, which counsels businesses on how their employees can achieve better performance through healthier rest. “It’s not a marathon; it’s more like a decathlon. It’s a thousand different things. It’s tempting to manipulate sleep with drugs or devices, but we don’t yet understand sleep enough to risk artificially manipulating the parts.”

Ellenbogen and other experts argue against shortcuts, especially the original one—the notion that we can mostly do without sleep. It was a glorious idea: If we could just cut the unnecessary parts of sleep, it’d be like adding decades to our life. In the early days of sleep science, the 1930s and ’40s, the second half of the night was considered by some to be the doldrums of rest. Some thought we might not need it at all.

That period turns out, instead, to be the wellspring of a completely separate but just as essential form of sleep, practically another type of consciousness altogether.

REM
In a wild state of psychosis, we’re dreaming, we’re flying, and we’re falling—whether we remember it or not. we’re also regulating our mood and consolidating our memories.

Rapid eye movement, or REM, sleep was discovered in 1953—more than 15 years after stages 1 through 4 had been mapped—by Eugene Aserinsky and Nathaniel Kleitman at the University of Chicago. Before then, because of its unremarkable pattern on early EEGs, this period was usually thought of as a variant form of stage 1, and not particularly significant. But once the distinctive eye darting was documented, and the engorgement of sexual organs that always goes with it, and it was understood that virtually all vivid dreaming takes place in this phase, the science of sleep was upended.

WHEN WE SLEEP
Visual journalist Magnus Wennman explores how three people around the world dream.
Generally, a healthy sleep begins with a spiral down to stage 4, a momentary return to wakefulness, and a five- to 20-minute REM session. With each ensuing cycle, REM time roughly doubles. Overall, REM sleep occupies about one-fifth of total rest time in adults. Yet stages 1 through 4 have been labeled as non-REM sleep, or NREM—80 percent of sleep is defined by what it’s not. Sleep scientists speculate that specific sequences of NREM and REM sleep somehow optimize our physical and mental recuperation. At the cellular level, protein synthesis peaks during REM sleep, keeping the body working properly. REM sleep also seems essential for regulating mood and consolidating memories.

Every time we experience REM sleep, we literally go mad. By definition, psychosis is a condition characterized by hallucinations and delusions. Dreaming, some sleep scientists say, is a psychotic state—we fully believe that we see what is not there, and we accept that time, location, and people themselves can morph and disappear without warning.

From ancient Greeks to Sigmund Freud to back-alley fortune-tellers, dreams have always been a source of enchantment and mystery—interpreted as messages from the gods or our unconscious. Today many sleep experts aren’t interested in the specific images and events in our dreams. They believe that dreams result from the chaotic firing of neurons and, even if imbued with emotional resonance, are devoid of significance. It’s only after we wake that the conscious brain, seeking meaning, quickly stitches together a whole cloth out of haphazard scraps.

Other sleep scientists strongly disagree. “The content of dreams,” says Stickgold of Harvard, “is part of an evolved mechanism for looking at the larger significance of new memories and how they could be useful in the future.”

Even if you never recall a single image, you still dream. Everyone does. Lack of dream recollection is actually an indication of a healthy sleeper. The action in dream sleep takes place too deep in the brain to register well on an EEG, but with newer technology, we’ve inferred what’s going on, physically and chemically. Dreams also occur in NREM sleep, especially stage 2, but these are generally thought to be more like overtures. Only in REM sleep do we encounter the full potent force of our nighttime madness.

Dreams, often falsely said to be just momentary flashes, are instead thought to span almost all of REM sleep, typically about two hours per night, though this decreases as we age—perhaps because our less pliant brains are not learning as much while awake and have fewer new memories to process as we sleep. Newborn infants sleep up to 17 hours a day and spend about half of that in an active, REM-like condition. And for about a month in the womb, starting at week 26 of gestation, it seems that fetuses remain without pause in a state very similar to REM sleep. All this REM time, it has been theorized, is the equivalent of the brain testing its software, preparing to come fully on line. The process is called telencephalization. It’s nothing less than the opening of the mind.

The body doesn’t thermoregulate in REM sleep; our internal temperature remains at its lowest setting. We are truly out cold. Our heart rate increases compared with other sleep stages, and our breathing is irregular. Our muscles, with a few exceptions—eyes, ears, heart, diaphragm—are immobilized. Sadly, this doesn’t keep some of us from snoring; this bane of the bed partner, impetus for hundreds of anti-snoring gadgets, is caused when turbulent airflow vibrates the relaxed tissues of the throat or nose. It’s common in stages 3 and 4 too. In REM sleep, whether snoring or not, we’re completely incapable of physical response, slack-jawed, unable to regulate even our blood pressure. Yet our brain is able to convince us that we’re surfing on clouds, slaying dragons.

Belief in the unbelievable happens because in REM sleep, stewardship of the brain is transferred away from the logic centers and impulse-control regions. Production of two specific chemicals, serotonin and norepinephrine, is completely shut off. Both are essential neurotransmitters, permitting brain cells to communicate, and without them, our ability to learn and remember is severely impaired—we’re in a chemically altered state of consciousness. But it’s not a coma-like state, as in stage 4. Our brain during REM sleep is fully active, guzzling as much energy as when we’re awake.

REM sleep is ruled by the limbic system—a deep-brain region, the untamed jungle of the mind, where some of our most savage and base instincts arise. Freud was right, in effect, that dreams do tap our primitive emotions. The limbic system is home to our sex drive, aggression, and fear, though it also allows us to feel elation and joy and love. While it sometimes seems as if we have more nightmares than pleasant dreams, this probably isn’t true. Frightening dreams are simply more likely to trigger our override system and wake us.

Down in the brain stem, a little bulge called the pons is supercharged during REM sleep. Electrical pulses from the pons often target the part of the brain that controls muscles in the eyes and ears. Our lids usually remain shut, but our eyeballs bounce from side to side, possibly in response to the intensity of the dream. Our inner ears too are active while we dream.

So are the parts of the brain that generate motion—which is why there’s frequently a sense of flying or falling in dreams. We dream, as well, in full color, unless we’ve been blind from birth, in which case dreams do not have visual imagery but remain emotionally intense. Men’s and women’s dreams seem to be similar in emotional content. Every time a man dreams, even if the content isn’t sexual, he has an erection; in women, blood vessels in the vagina are engorged. And while we dream, no matter how absurd, despite all transgressions against the laws of physics, we’re almost always convinced we’re awake. The ultimate virtual-reality machine resides inside our head.

Thank goodness we’re paralyzed. When you dream, your brain is actually trying to produce movements, but a system in the brain stem completely shuts down the motor-neuron gate. There’s a parasomnia—a sleep abnormality that affects the nervous system—called REM behavior disorder in which the gate does not fully lower, and people act out their dreams in spectacular fashion, punching, kicking, swearing, all while their eyes are closed and they’re fully asleep. This often results in injuries to the sleeper and his or her bedmate.

The end of a REM session, like the end of stage 4, is usually marked with a brief awakening. If we rest naturally, without an alarm clock, our last dream of the night often concludes our sleep. Though the amount of time we’ve been asleep helps determine the optimal moment to wake, daylight has immediate alerting properties. When light seeps through our eyelids and touches our retinas, a signal is sent to a deep-brain region called the suprachiasmatic nucleus. This is the time, for many of us, that our last dream dissolves, we open our eyes, and we rejoin our real life.

Or do we? Perhaps the most remarkable thing about REM sleep is that it proves the brain can operate independently of sensory input. Like an artist ensconced in a secret studio, our mind appears to experiment without inhibition, let loose on its own personal mission.

When we’re awake, the brain is occupied with busy work—all those limbs to control, the constant driving and shopping and texting and talking. The money-earning, the child-rearing.

But when we’re sleeping, and we commence our first REM session, the most elaborate and complex instrument known in the universe is free to do what it wishes. It self-activates. It dreams. This, one could say, is the playtime of the brain. Some sleep theorists postulate that REM sleep is when we are our most intelligent, insightful, creative, and free. It’s when we truly come alive. “REM sleep may be the thing that makes us the most human, both for what it does for the brain and body, and for the sheer experience of it,” says Michael Perlis.

 

 
Summary from 16 Chronological Tips to Improve Your Sleep

Lack of Sleep Can Leave You Functionally Drunk

Results of a recent University of Michigan study, which found even six hours of sleep a night is too little and may leave you functionally impaired, similar to being drunk. University of Michigan mathematician and study author Olivia Walch said:¹

“It doesn’t take that many days of not getting enough sleep before you’re functionally drunk … Researchers have figured out that being overly tired can have that effect.

And what’s terrifying at the same time is that people think they’re performing tasks way better than they are. Your performance drops off but your perception of your performance doesn’t.”

Smartphone App Reveals Insights Into How the World Sleeps

In 2014, Walch and colleagues released a free app that recommends optimal lighting schedules for adjusting to new time zones (i.e., helping to reduce the effects of jet lag).

The app, called Entrain, asks users to input their sleep times, home time zone and typical lighting schedule, and it can also record hourly light and sleep schedules.

This might not seem like a large discrepancy, but even 30 minutes of extra sleep can make a big difference in your health and ability to function. Other interesting facts revealed by the study included:³

• Middle-aged men got the least sleep and often slept less than seven to eight hours a night.
• Women tended to schedule more time for sleep and slept about 30 minutes more per night than men. Women tended to go to bed earlier and wake up later.
• People who spent time in the sunlight each day tended to go to sleep earlier and got more sleep than those who spend most of their day indoors.

Trends were also noted by age, which suggests your biological clock may influence your internal clock. In particular, the researchers noted that people’s schedules dictated their bedtime but their internal clock governed their wake time.

Therefore, the best way to get more sleep is to go to bed earlier. Study co-author Daniel Forger, Ph.D., of the University of Michigan explained:

“Across the board, it appears that society governs bedtime and one’s internal clock governs wake time, and a later bedtime is linked to a loss of sleep …

At the same time, we found a strong wake-time effect from users’ biological clocks — not just their alarm clocks. These findings help to quantify the tug-of-war between solar and social timekeeping.”

1 in 3 U.S. Adults Don’t Get Enough Sleep

In this case, “enough” sleep was defined as seven or more hours per night, but many adults may need closer to eight hours per night (and thus lack of sleep may affect even more than one in three adults). Research has found that when participants cut their sleep from 7.5 to 6.5 hours a night, there were increases in activity in genes associated with inflammation, immune excitability, diabetes, cancer risk, and stress.⁵

Poor or insufficient sleep was even found to be the strongest predictor for pain in adults over 50.⁶Interrupted or impaired sleep can also:

• Increase your risk of heart disease and cancer
• Harm your brain by halting new neuron production. Sleep deprivation can increase levels of corticosterone (a stress hormone), resulting in fewer new brain cells being created in your hippocampus
• Contribute to a pre-diabetic, insulin-resistant state, making you feel hungry even if you’ve already eaten, which can lead to weight gain
• Contribute to premature aging by interfering with your growth hormone production, normally released by your pituitary gland during deep sleep (and during certain types of exercise, such as high-intensity interval training)
• Increase your risk of dying from any cause

Here’s the chronological list, starting with when you wake up and continuing until bedtime.

Sleep Habits of Rich and Famous

How the World Slept Timeline