The Importance of Sleep

A while back my brother was mentioning that one of his friends slept for only a few hours a night, and she didn’t understand the importance of sleep or how our body’s cellular clock works. Around that time I was doing some readings on the circadian rhythm, so figured to write a blog about the importance of sleep.

According to the National Sleep Foundation, around 47 million Americans do not get enough sleep. Such sleep deprivation results in injuries and decreased productivity, which can cost the country 18 billion dollars a year. Lack of sleep also contributes to 1.2 million car crashes a year, 20% of the annual total for all car crashes. A report in the NY Times says sleep deprivation causes over $400 billion in economic losses each year.

I will first start with the two different types of sleep. They are – non-REM sleep and REM sleep. REM sleep, short for Rapid Eye Movement sleep, is where most of our dreaming happens. Ever saw someone sleeping while their eyeballs are moving rapidly and wondered if and what they might be dreaming about? That’s REM sleep.

Stage 1 non-REM is light sleep lasting for 1 to 7 minutes where we can be woken up by someone calling our name. Our heartbeat, breathing, and eye movements start slowing down. Our muscles start relaxing and our brain waves also slow down.

Stage 2 non-REM sleep is another period of relatively light sleep lasting for 10 to 25 minutes. But awakenings are harder to occur in stage 2 than stage 1. Our muscles relax even further and our body temperature starts dropping. We spend more time in stage 2 non-REM sleep than any other stage. Although our brain waves continue to slow down, there are bursts of rapid electrical activity thought to protect the brain from awakening from sleep.

Stage 3 non-REM sleep is the deep sleep phase. This stage lasts about 20 to 40 minutes and is very difficult to wake someone up from. This is also the most restorative stage of sleep where the body heals itself from the stresses of the day.

After stage 3 non-REM sleep, the body transitions to a few minutes of stage 2 non-REM sleep before moving on to REM sleep, which first occurs around 70-80 minutes after falling asleep. Eyes move rapidly and brain wave activity increases. Breathing, heartbeat, and blood pressure also increase to near waking levels. This is also the stage where most of our dreaming occurs and our body becomes paralyzed so we don’t physically act out our dreams. As the night progresses, the amount of time we spend in stage 3 non-REM sleep decreases while our REM time increases. In the beginning part of the night a complete sleep cycle might be 70 to 90 minutes, gradually increasing to 90 to 120 minutes as the night goes on. As such, on a typical night we might get 5-6 full cycles of sleep.

What happens if we sleep too late at night? Our body’s sleep cycle spends more time in REM stage than in stage 3 non-REM deep sleep stage. That’s why if we don’t sleep enough, we don’t feel refreshed when we wake up.

Next I’ll talk about the biology of sleep. Sleep is controlled by two systems in our body – homeostatic sleep drive and the circadian rhythm.

Homeostatic sleep drive is a simple process to understand – the longer you have been awake, the more likely you are to fall asleep. While there are numerous biochemical processes that drive the homeostatic process, one of the mechanisms that would be familiar to us is the role of adenosine in sleep. Adenosine is released throughout the day by the energy giving molecule ATP. The more physical work we perform, the more ATP is broken down in muscles to produce Adenosine. And we all know how quickly we fall sleep after a physically tiring day! All the adenosine released from the breakdown of ATP binds to its receptors in the brain, releasing other chemicals that make us fall asleep. In contrast, caffeine competitively binds to the same receptors as adenosine, thereby blocking the actions of adenosine. There are other mechanisms of caffeine where it releases hormones that make us more alert in the morning, but by binding to adenosine’s receptors, caffeine plays an important role in negating the drowsiness of late afternoons.

The circadian rhythm is an internal clock that follows a 24-hour cycle. This rhythm affects every cell, tissue and organ in the body, and is controlled by a master clock. This master clock consists of a group of 20,000 neurons called the suprachiasmatic nucleus (SCN) and is located in the hypothalamus of the brain. As seen in figure 1, this region receives light directly from the eyes through the optic nerve. The SCN subsequently sends signals to other locations in the brain that control hormones and the body temperature. One of the locations the SCN transmits signals to is the pineal gland where melatonin is produced. This hormone is involved in wakefulness, and its production is switched off during the day when the SCN is sending signals to the pineal gland. In the absence of light, melatonin production is ramped up and we fall asleep. Because the circadian rhythm starts producing hormones that make us fall asleep as the evening wears on, eating late at night produces hormones that make us stay up later, and as such disrupting our circadian rhythm and the sleep cycle.

1416593790081

Figure 1: Light reaching the SCN via the optic nerve. Image from American Chemical Society

The rhythm and timing of the circadian rhythm also changes as we age. Melatonin is released later in the night in teens, causing them to sleep and wake up later. As we get older, melatonin is released earlier in the evening. Therefore, we can blame melatonin as to why old people fall asleep and wake up earlier than adolescents! The amount of sleep we need also varies with age. Newborn babies need nearly 16 hours of sleep. Young children and teens need 8 to 10 hours of sleep, while older adults don’t need more than 7-8 hours of sleep. For most people, 7 to 9 hours of sleep is most appropriate during the day. Averaging under 6 hours or over 9 hours has been associated with increased mortality. As with anything in life where balance is important, 7 to 8 hours of sleep at night, or 7 hours of sleep at night and 30 to 90 min nap during the day is the ideal way to get an adequate amount of sleep and feel well rested.

sleeptimerecommendations_chart_final

Figure 2: Recommended sleep durations

I am a fan of afternoon naps. Our circadian rhythm causes a dip in energy around 2 to 4 pm for most adults. This is when we feel tired after lunch. It isn’t just our food that makes us sleepy, but most of us are programmed to be sleepy in early afternoon. This is also a perfect time to nap because we spend more time on stage 1 and stage 2 of non-REM sleep, and some time in REM sleep. If we nap late in the evening, we tend to spend more time in stage 3 of non-REM sleep, or deep sleep. No wonder we wake up feeling groggy!

You may be wondering, how long is an appropriate nap time. That would be about 20 minutes, or 90 minutes. A 20-minute power nap would keep us in stage 1, or light sleep, and it improves our alertness, enhances our performance, and gives us better mood. And if you do have time, take a 90-minute nap which is a full sleep cycle. You would wake up feeling refreshed, and a full cycle nap boosts memory as well as our creativity. If you are feeling tired in the afternoon, don’t feel bad. Its just the body going through its cycle. And maybe tell your boss that you should take a nap for even better performance!

While researching for this topic, I came across sleep paralysis. I had experienced it numerous times but didn’t know what it was called. Probably about once a month I would wake up in the middle of the night with a sense of dread, and I would think a thief is in my room. I would try to move my body, scream, but my entire body would feel paralyzed. Well, what happens is that in REM sleep the body goes into a state of paralysis known as REM atonia. As mentioned above, REM sleep is where we have most of our dreams. Because the body is paralyzed in REM sleep,  we don’t act out on our dreams by kicking or lashing out. Ever had someone sleeping next to you kick you in the middle of the night? That’s them dreaming and their REM atonia not fully functional.

Scientists hypothesize that sleep paralysis occurs when transition from REM sleep to other sleep phases don’t go smoothly. The paralysis of the body in the REM spills over to other stages, and if we wake up in that stage we become aware of our paralysis. Why we feel scared and feel there is someone or ghost-like presence in our room, for that science doesn’t have an answer yet! But after learning this, the next time I wake up with sleep paralysis, hopefully I won’t feel scared that there is a burglar in my room!

Most of us have heard how lights from our electronic devices can negatively affect our sleep. When I turn on night mode on my iPhone or Windows computer, the screens turn into a yellowish tint. White LED light, or blue light in the electromagnetic spectrum, with its shorter wavelength and higher energy, have been implicated in suppressing melatonin and affecting our circadian rhythm. As seen in figure 3, the solar spectrum is mostly in the green-yellow wavelength, while candlelight as well as incandescent lightbulbs emit wavelengths mostly in the red region of the electromagnetic spectrum. This red light has the least power to shift the circadian rhythm and suppress melatonin. Researchers have found that exposure to blue light (white LED light) compared to green light (sunlight) can suppress melatonin twice as long. In contrast to white LED light, midday exposure to sunlight helps in releasing melatonin at night. Researchers have shown that office workers in windowless environments have lower sleep quality than those exposed to sunlight during the day. To get a good night’s sleep, it is ideal to avoid looking at our electronic devices two hours before bed, or wear blue-light blocking glasses or installing apps that filters blue/green wavelength at night and switching to dim, yellow/red lights. But blue light can have some useful purposes. It has been used in light therapy to boost attention, reaction time, mood, depression, as well as seasonal affective disorder.

spectral

Figure 3: White LED spectrum vs Solar spectrum. Image from ExtremeTech.com

This brings me back to the last topic, the actual health effects of sleep deprivation. Lack of sleep can cause a lot of problems such as obesity, diabetes, hypertension, and compromised immunological function. It also affects our ability to form memories. Lack of sleep or poor sleep increases the production of the stress hormone cortisol. It also increases release of insulin, a hormone that promotes fat storage. Insufficient sleep also causes lower levels of the hormone leptin, and higher levels of the hormone ghrelin. In combination, this causes food cravings and contributes to weight gain. We all know lack of sleep causes mood disorders such as crankiness and irritability. Lack of sleep can cause safety hazards at the workplace or road mishaps, among other things. A proper night’s sleep, as well as a full REM-cycle nap, helps in forming memories. It improves are mood and learning abilities.

Hopefully I have given some ideas about the importance of sleep. Going to sleep at an appropriate time, eating at least couple of hours before sleep, avoiding blue light before sleep, taking naps when possible, these are all important conditions when creating a healthy sleeping habit.

 

 

 

 

Evolution or Creationism?

A few weeks back a friend asked me if I believed in creationism or evolution. I did not answer because I do not think that a simple “yes or no” answer, without context, really answers something that is as complicated and controversial as this topic. There are many good and intelligent people who do not want to be anti-science, many who do not have an issue with microevolution, but are uncomfortable with macroevolution and speciation, especially human speciation, because of deeply held theological beliefs. A while back a friend told me that she saw on a Pakistani TV channel a debate between a scientist and a religious figure. According to her, the scientist told the religious man – “This is what science says. What you do with the information is up to you.” I will try to do that. Evolution is extremely complicated and there are numerous fields of science that confirm it. I will try to explain at a layman’s level so it is easier for anyone with school level biology education to understand.

Evolution:

When thinking about evolution, I think it will be easier to focus on “isolation” and “generation time” than on size of the organism. This is because many people can imagine microbes becoming different strains, but can’t imagine a large animal evolving into something else. People usually mistake ‘transformation’ or ‘metamorphosis’ with evolution. Probably that is why they wonder ‘if monkeys evolved into humans, why are monkeys still there’. This is a sad aspect of our education system. Monkeys do not turn into humans. Chimpanzees and we share a common ancestor. But how?

Mutations are always happening in our body. Some mutations are advantageous while some are not. That is where our “natural talent” for something comes from, or our individual traits like hair color or eye color. When any two groups of the same species are separated for an extremely long period of time, mutations in both groups start accumulating. Natural selection happens when a certain mutation allows that person to pass down his/her genes to his/her offspring. “Survival of the fittest” is a wrong phrase in describing evolution. The better phrase would be “survival of the one most likely to pass down his genes in this particular ecological niche”. If a small group of humans wander off to a forest where all the fruit-bearing trees are tall, eventually every individual in that group is going to be tall. Anyone who is not tall enough will be at a disadvantage for sustenance. So children who grow to be tall are more likely to survive and find mates and pass down their tall genes. It is the same way we are different races and have different features. Someone in Turkey has different features compared to someone in China. There are, and have been, many indigenous groups whose adults barely reach five feet in height. These differences in features happen because of separation of one group from the other, and inbreeding in an individual group. If Koreans only bred among themselves, they will maintain their features that will be distinctive from the Han Chinese who might breed only in their own group. These features develop over hundreds and thousands of years. Evolutionary scale for large animals like us with longer generation gap is in the millions of years. That is why our nearest common ancestor to the chimpanzees lived a few million years back. In this time, we have had other “relatives” in the hominid family. We even bred with some of them, like the Neanderthals. And that is how evolution works – slow branching out among members of a family. In our daily lives we see members of the canine families, like dogs and wolves, and we have members of the feline family like cats, lions, and tigers. Even though they are different species, we see it every day how much traits they all share. They might have evolved to be different species, but they came from a common ancestor. And therefore they share the similar genes, the way we share genes and features and traits with members of the primate family.

Let us get back to mutations. Our DNA has about 3 billion base pairs. Each base pair – A, T, C, G – is the alphabet of life. A combination of three of those bases code for an amino acid, and thousands of amino acids arrange themselves into a protein. When each cell in our body divides, the DNA gets replicated. But the enzyme that is involved in the replication – of adding the A, T, C, G base pairs to new strand of DNA, makes mistakes. Most of those mistakes are repaired by other mechanisms, but some mistakes still remain. Sometimes these mistakes can cause serious harm. But these mistakes do not pass down to our offspring. Only the mutations in the sperm and the egg pass down to our children. Each mature egg has divided about 30 times from the time it was a zygote, and it has accumulated about 9 mutations along the way. Each sperm has divided about 400 times for a total of 120 or so mutations. So every time a baby is conceived, the zygote already has about 130 mutations. These mutations can be completely neutral, they can be fatal, or they can introduce new genetic traits missing from the parents. If this person has many offspring, there is a huge probability of those traits being passed down. And the traits associated with the mutation become part of the gene pool. But if that person had a mutation for an IQ of a 200 but he/she did not have any children, that mutation goes out of our gene pool. Passing down such traits through breeding is what gives characteristics to certain groups.

This is microevolution. What how does speciation happen? Besides separation between groups over large periods of time, it would be easier to understand speciation by understanding generational time. It takes time for mutations to accumulate that might give an individual, and then a group, advantage in a certain geographical niche. And that time depends how fast that particular species replicates/reproduces. Viruses and bacteria replicate really fast – many in a matter of minutes. For such microorganisms, thousands of generations can be produced very quickly. If they have a high mutation rate, it might be hard to develop drugs for them because the virus can change a lot in a short period of time. That is one of the biggest problems in developing therapies for HIV. For human beings, each generation is about 20-25 years. For thousands of generations to pass, we would be looking at hundreds of thousands of years! That is why imagining evolution in higher animals is hard. It is much easier to see it in birds or frogs or even fruit flies. We have even done experiments in fruit flies to show macroevolution. And the best example might be the evolution of dogs from wolves. In about 10,000 years, we have domesticated wolves and bred them every way possible to create so many kinds of dogs! Evolution is the reason why native populations were decimated because of diseases from other continents. People in the new places did not evolve with the diseases; therefore they did not have the antibodies to protect them. Evolution is also the reason why we have so much good bacteria in our body. We co-evolved with them in a symbiotic relationship where they produce enzymes and vitamins, while they use our body for sustenance.

The three basic concepts of evolution are mutation, reproduction/generational time, and competition (or having the traits most likely to survive and breed). Obviously, this is a very short introduction to evolution, but this is the basic biological mechanism of evolution.

Creationism:

I asked the same friend about evolution and Genesis. As a follower of an Abrahamic faith, she said she took Adam and Eve as literal stories, and as a biologist she also agreed that evolution is true. And to give her credit she then said – “I never thought about them both at the same time. But both cannot be true. It is evolution that is true, not Adam and Eve.” Then how do so many people disagree with her? I cannot comment on a singular creationism story because over the course of human history every group has had its own creationism stories. It would be intellectually dishonest of me to debate between Darwin’s theory of evolution and Genesis, which is just one story out of hundreds. Similarly, it would be intellectually dishonest to give credence one group’s beliefs while refuting other beliefs. Let us take the story of Genesis. Officially, just about 55% of the global population follows the Abrahamic religions. And many of them do not take their Scriptures literally. And when we hear about the controversy in the West or in the Islamic world, it is either evolution or biblical story of Genesis. This ignores the fact that half the world does not believe in that story, and that there are as many creation stories as there are have been ancient cultures in this world. To those who say that children should learn “both sides of the story”, which creationism stories should we teach? Or do you only want your creation story to be taught. For some religions like the Dharmic religions of South Asia, or for animism and many others, evolution lines up even better when you consider reincarnation. For many philosophies Hinduism or Buddhism, the human body means nothing. It is the soul that is reborn in various animals and ultimately achieves a release from the cycle of rebirth. And Hinduism isn’t even a singular faith. One can find monotheism, polytheism, agnostism, and atheism within different aspects of Hinduism. Therefore, the idea that Genesis is the only other alternative to evolution seems to be hollow and intellectually dishonest. And I am not advocating other religions. My point is to show that there are countless beliefs and a lot of them have no contradiction or no opinion on creationism vs evolution. So why should we discard their views?

Finally, the idea what evolution is a “theory” so it shouldn’t be taken seriously, or that there are gaps in it are an illogical and flawed arguments. In scientific terms, “theory” is a hypothesis that has been repeatedly tested and withstood every test. Evolution is one of the strongest theories in all of science. No one ever complains about many other scientific theories that aren’t as strong as evolution. People jump into the latest fad about diet or beauty products with faux scientific principles and no one complains. Newton’s gravity breaks down as we approach the speed of light, but we still teach it in schools because for most practical purposes it works fine. Einstein’s relativity breaks down at the quantum level, but we still accept relativity because outside of the quantum level it works fine. And we have yet to fully understand quantum mechanics. From my perspective, the singular focus on evolution exists because it targets people’s faith/beliefs, not because of its scientific inadequacies. I have heard time and again support for creationism because of how “perfect” the human body is. But is it really? Besides our intelligence and our opposable thumbs, our body is hardly the best physical specimen. We are neither the strongest, nor the fastest. Our natural lifespan (before the onset of medicines and healthier diet and agriculture) is comparable or even lower compared to many other animals. And eyes aren’t the best, nor our sense of smelling or hearing. Our immune system cannot fight off emerging and zoonotic infections. Our brain hasn’t yet evolved for a long lifespan, therefore the cases of Alzheimer’s. Many of us have genetic predispositions for so many illnesses, including cancer. So how exactly is our body the “perfectly crafted specimen of a God”? We have vestigial organs like appendix which has lost its function through evolution, and which can actually cause life-threatening harm. The human body is imperfect, but it is constantly evolving and getting better.

Scientists (and me):

Scientists must also stop being arrogant when discussing creationism, evolution, or theology. People have the right to their beliefs. Many of us overstep our scientific boundaries and think religious people are stupid, or make blanket statements about beliefs that cannot be disproven by science. For example, whether there is a God or Gods/Goddesses or any supernatural being cannot be proven or disproven by science. If people want to believe in fairies and monsters, we must let them because it is their right. Science cannot quantify the supernatural; it must only stick to the natural world. Whether there is a supernatural world or not is the field of theologians and philosophers.

But on the same token, scientists must stick up for the natural world. Everything in our universe follows laws and order. Even the disorder of nature follows scientific laws. There are no miracles, but only probabilities. From everything we know about our universe, there are no supernatural phenomena in our natural universe. Scientists must stand up for the teaching of the natural world in our schools, and they must stand up against individual beliefs being taught in public schools or being passed off as science. For a scientist, evolution is the best theory of how human beings came to be. But a scientist cannot and should not answer why are we here or what is the meaning of life or what is there after life. And scientists must be humble to the fact that a new discovery tomorrow can disprove evolution. There is much to learn about evolution, just like any other topic in science. Just because we do not have the answer does not mean something is wrong. We are on the right track. If having all the answers was a requirement, then nothing could be taught in schools because science itself is evolving with new information and new understanding. But if evolution is wrong, will it prove creationism? No. Because it would bring me back to my original question – whose idea of creationism should we follow if evolution is wrong? And if evolution is wrong, we must teach in our schools whatever scientific theory replaces evolution.

Scientists must also understand that humans are a spiritual species. Our intelligence and self-awareness makes us ask questions that a study of the natural world will never be able to answer. For me personally, as a formerly religious and a currently spiritual person, this hasn’t been an easy journey. If someone truly believes in the Abrahamic religions’ story of Genesis, the question “if Adam and Eve are not real, then…” can be a very tough one. It certainly is an extremely scary thought, because it goes to the foundations of these religions. And I do not have an answer to give others for such deep and personal questions. I didn’t grow up in an Abrahamic faith, but I have faced my own share of questions in the last 10-12 years. It has been a torturous journey, from being quite religious to finally coming to terms that religion and science cannot be compatible. For the simple fact that every religion is different from another religion, and picking and choosing parts from one religion and not from another to make it compatible with evolving scientific theories is too intellectually dishonest for me. 10 years later I still do not know what is true; all I am sure of is what is not true. I am slightly less peaceful than before, but I am definitely happier than before. I might not know the answers to our existence, but at least I feel I am no longer self-righteous and stubborn about my theological beliefs. Every person has gone through or will most likely go through these questions. And scientists must respect these philosophical and spiritual journeys. When it comes to evolution, I have come across six reactions – 1. Completely reject evolution; 2. Accept microevolution but reject random macroevolution and instead believe in intelligent design; 3. Accept evolution of other species but not in humans; 4. Rather than taking Adam and Eve literally, try to find the meaning of their existence in the earliest of humans;  5. Call one self somewhat religious but not take Scripture literally and accept that it is written by men; 6. Accept science, reject religion and/or its doctrines. And I think nearly everyone falls in one of those six categories. And I am quite sure most think their category is the Right or True one.

This essay won’t change anyone’s mind. But I hope it makes some people think. And hopefully a few of that subgroup will allow their children to accept what is taught in a public school science classroom, rather than tell these kids that science is wrong. That is how change takes place. As far as the future goes, I am confident evolution will be accepted the way heliocentrism has been and many other issues. Without wanting to bring more controversy to this topic, there have been many “self-evident” beliefs and actions, practiced for centuries, that are no longer considered true. Religions have ‘re-interpreted’ many former beliefs to ‘evolve’ with changing times. I am confident evolution will reach that stage very soon. The foundation of modern biology is built on evolution. And for a society to progress, it cannot treat scientific theories as a choice. By the middle of this century I can foresee evolution being accepted in even the most conservative societies of today. In modern biology and medicine, nothing makes sense except in the light of evolution.