Sleep II
When I was visiting England recently, at dinner one evening we spoke about how it is difficult to get a human answer the customer service helplines since it has all been more or less automated. If a human does answer the phone - it will mostly be someone from India, helping you solve your problems. The Call Centers are synonymous with India - companies can afford to outsource medium-skill tasks to countries with cheap labour for a good looking bottom line. This sadly has resulted in many many young adults in India completely changing their sleep rhythms and their concepts of days and nights to work at these call centers to be able to serve customers from the West. The Circadian Rhythm, one of the factors that signals the body when it needs to sleep and when it needs to be awake, is forcibly twisted and turned on its head - to behave exactly opposite to how it has been behaving for millennia now.
What is the circadian rhythm?
Think of it as an internal clock that is constantly running in the background, letting your body know when it needs to sleep and when it needs to be awake. Most folks term it as the sleep/wake cycle. The word Circadian can be broken into two : circa meaning around and dian meaning day. The definition then means that this internal clock is "around" 24 hours long In many experiments, that Matthew Walker shares in his book - it has been established then the human body has a rhythm that is a little longer than a day - in the absence of sunlight as a trigger for the sleep/wake cycle, humans repeated the sleep and wakes cycles and they were consistently longer than 24 hours. The sunlight then helps the brain rewire that internal clock to an exact 24 hours which works for us to match our internal and external activities to the rising and setting sun.
This internal clock that manages this rhythm is located in the middle of the brain and is called the Suprachiasmatic nucleus. Matthew Walker states that the "circadian rhythm activates many brain and body mechanisms in the brain and body during daylight hours that are designed to keep you awake an alert. These processes are then ratcheted down at nighttime, removing that alert influence."
For eg - the body's core temperature drop as we get closer to our bedtime, and when it's time to wake up (and it's also daylight) the temperature begins to rise, the drop in temperatures will help initiate the sleep. Now this happens irrespective of whether you sleep or not - which means that the circadian rhythm control the sleep and wake cycles and not the other way around.
I was speaking to a couple of friends over dinner two days back and they said, they're both not morning people and that their peak alertness and wakefulness times are mid afternoon and evening and that try as they might, they can not adapt to a 10pm sleeping and 7 am waking up schedule - even though that is believed to be the healthiest times to sleep in.
Now, yoga scriptures state that the ideal time to be up is 4:30 am - Brahma Muhurta - I've spoken about this when i wrote on Swara Yoga.
The book states, backed by data of course, that every person has their own circadian rhythm and they very well might be evening or morning types. This is sadly not something they can change and is often wired by their DNA and determined by genetics. With this new knowledge, I will have to re-analyse the Brahma Muhurta timing - let's see where I can find more info on why 4:30 am is good and if it really is.
The book does touch upon how the modern work schedule disadvantages people who are genetically night owls - because they can't go to sleep until really later and they have to wake up by 7 or 8 to get to work for a 9 am start, which as we will learn as we discuss the chapter further - causes much mental distress and health problems.
Three more topics to discuss in this post, one of which is a very touchy subject for me, because I know I am guilty- caffeine!
Let's avoid talking about of caffeine for now and start with Melatonin.
Meltonin is a hormone released by the Pineal gland at night and helps let the body know when to go to sleep and when to be awake. Now it is important to note that it does not do the work itself - it helps the body start the processes that signal wakefulness and sleep - like a trigger that says "ok, off you go, do your job now". The suprachiasmatic nucleaus situated in the middle of the brain, which is also the crossing points for the optic nerves coming from your eyeballs - as shown in the below pic. When the retina and hence the suprachiasmatic nucleus registers darkness outside, it sends a signal to the pineal gland to start the secretion of Melatonin. Similarly, when it is light outside, the pineal gland is instructed to stop secreting melatonin.
sources BioNinja.com
Next up, jet lag & sleep.
I'll use an example similar to the one Matthew Walker uses in his book about travelling westwards. When i travelled from India to London last month, I also travelled 4.5 hours behind my regular Indian clock (i was about to say 4.5 hours back in time - but that wouldn't be technically correct would it?). When I arrived, I was doing ok since i got in the morning hours and it was daytime in London and India both. 4.5 hours is not a huge deal, but when it's 7:30 pm in London it's midnight in India and that is when it began to hit me really hard. I was trying to stay up to adjust to the new timezone, but I couldn't last beyond 9pm - which in itself is quite tremendous knowing my lack of willpower when it comes to staying awake.
Now eventually my body will adjust itself to this new time zone and I don't have be a zombie post 7 pm every day, but as the book states "For every day you are in a different time zone, your suprachiasmatic nucleus can only readjust by about an hour". Which means, I will need approximately 4-5 days to get into the London rhythm. I thankfully do not have to do many transatlantic flights or even fly frequently to Europe from Asia, but I worked for an organisation when people did that all the time. Sometimes, twice a month from Singapore to SFO - which is a huge timezone difference, so by the time your body is ready to adjust (8-10 days), it is time to head back and then fly out very soon again shocking the body with an 8 hour time difference. Most folks would wave their hand when I remarked at their ability to travel and say stuff like "We shall sleep when we die or when we are old" or some stuff like that. I should mail them all a copy of Why We Sleep as an early Christmas or Diwali present.
It is however, easier when you are travelling westwards, because the time zone difference usually means you need to stay up longer. Whereas if you were to fly eastwards, you will have to go to bed earlier - which barring some of us is hard to do. Quoting the book again " Our natural Circadian Rhythm is innately longer than one day.................... this makes it artificially stretch a day then shrink it". Matthew Walker, also quotes a study on airline crew who have to go through these situations more often than even my ex-colleagues, results showed impairment of short term memory and destruction of brain cells relating to memory and learning. When I was very little, one of the things I wanted to be was an air-hostess, I was so intrigued by how pretty they looked and how polite they were and how they got to travel the world. I am sure my body and brain thank me for not pursuing that career. But, it does make me appreciate the crew that make it possible for us to get to opposite sides of the world, unfortunately at their own peril.
Now, that I have dilly-dallied enough, time to get to caffeine. Those who know me know I love my tea and coffee. A lot. I can drink many cups and i always used to pride myself on it not affecting my sleep. Either I have to be one of those rare souls that the universe has blessed or I've been fooling myself. Chances are the latter is true.
Before, we go into caffeine itself, we shall talk about Sleep Pressure. The second factor controlling our sleep and wake times along with the circadian rhythm. The longer you awake, the more a certain chemical called adenosine will accumulate in your body (for a short summary, read this and for a more scientific study, read this). As adenosine builds up in the bloodstream, it interacts with certain cell receptors and inhibits neural activity and causes drowsiness - letting us know when we should go to sleep.
No caffeine is known to be an adenosine blocker - it latches onto the same receptors that adenosine attaches itself to - thereby preventing the drowsiness that occurs due to an increased adenosine level.
The book speaks about the half-life of caffeine - which means how long does it take for half or 50% of the caffeine to be removed from your system. The answer is 5-7 hours. I found that astounding. it takes 5-7 hours to remove 50% of the caffeine i had, that still means the other 50% is still there. No wonder the 5 pm coffee or tea, causes you to lay awake in bed wondering why you are not being able to sleep, even though you might be tired!
So how does the body get rid of the caffeine? The liver has an enzyme that helps with processing caffeine in the body, "allowing the liver to clear it from the bloodstream". The lucky souls I spoke of earlier who can sleep very soundly even with massive amounts of coffee & tea during the day are people who have a very effective version of the enzyme and as predicted those people are very far and few in between.
Now, the caffeine will temporarily block the adenosine in the body, but it will eventually be broken down and when that happens, all of the adenosine that your body was accumulating prior to the caffeine PLUS the amount post the caffeine will hit you together. Matthew Walker calls it a "caffeine crash". Most of us then go on to consume more caffeine getting ensnarled in the vicious fangs os substance dependency. I'm stretching it too far you say? After all caffeine is not exactly heroine Mr. Walker again quotes a study done by NASA which can be read here. The images are below :Can
Can you believe this. I mean, take a second to look at those pictures again. When i first read the book, I gave up coffee for two days (i still cheated with tea) - it shocked me immensely. And as Matthew Walker says, it is the only stimulant drug that we so readily offer our children. I'll let you digest that for a few seconds before you can move on to the closing topics for this post.
All the accumulated adenosine does eventually get cleared from your body as you sleep - "after approximately 8 hours of healthy sleep in an adult. the adenosine purge is complete". Which explains why if you haven't slept enough, you sometimes wake up feeling really groggy because the adenosine in the body hasn't had a chance to clear up and is still causing drowsiness.
As a wrap, we've discussed two factors that affect sleep and waking schedules and patterns - circadian rhythm and the sleep pressure caused by adenosine build up in the body. These however, the book shares, are unrelated to each other. The circadian rhythm for example will continue flowing in it's 24-hour cycle without regard for whether you have slept or not, whereas the Sleep pressure will keep increasing the longer you stay awake. Matthew Walker uses the Borbely Model to explain how the circadian rhythm and the sleep pressure work together to induce sleep (refer to the cute little image below)
Source : Research Gate
The curve on top is the Sleep Pressure (S) and the curve below is our circadian rhythm (C). The more the distance between them, higher your likelihood of sleep.
To end, the book mentions a questionnaire that will allow you to figure out your sleep fulfilment, it is called SATED and is used world over to assess sleep score. I, however, did not find it all that useful. Here it is below :
What i did quite like was this survey : Great British Sleep Survey. Yes, I know it's a ridiculous name but it is quite effective and backed by Oxford University - that should count for something right?
This is me signing off, until the next instalment. Sleep Well!
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