Curious Sam
Daysleeper; Circadian Rhythms in a nutshell

In my other tumblr blog (unclesamsrants.tumblr.com) I write blog entries about various things that annoy me. These rants, however fun to write (and sometimes necessary), sometimes spark thought processes that transcend blind rage. I’ve decided to devote another blog to the other prominent side of me, which is that of science. So, I will be taking my various rants (or musings) and shedding some scientific light on some of the issues they raise.

This issue is all about circadian rhythms, this is in response to my rant about morning people, and how I’m not one. Circadian rhythms are interesting because they explain sleep, tiredness, and a distinct abhorrence for loud noises in the morning, in a scientific way.

Firstly, there are two main sections to this post, the first is melatonin, which is a hormone mostly responsible for causing tiredness and make you want to sleep. The second section is clock gene expression, which is how the cells in our bodies develop 24 hour cycles (even without light).

Melatonin
Melatonin is known as the “darkness” hormone, as it is produced when there is a lack of light, and it is inhibited by light exposure. The effects of melatonin are that it causes drowsiness and lowers body temperature. Melatonin is therefore a big player in why we get tired at night, and it is also the culprit when we feel tired in the morning. If we have to wake up before daylight, we usually wake up with high levels of melatonin, which is why we’re still tired. It isn’t until it starts to get light do we start to feel awake (as melatonin production is inhibited and cleared from the blood by the liver).

Indeed melatonin does have a fair bit to account for. Remember when you were a teenager, and how difficult it was to get up in the morning? It seems that between childhood and the teens, the production of melatonin can be delayed, which is why teenagers stay up longer, and also why they find it harder to get up in the morning. One positive outcome from this knowledge is the discovery that specific light frequencies seem to inhibit melatonin, specifically blue light. Exposure to blue light in the morning can make mornings more bearable, and wake you up a bit quicker.

Of course, melatonin isn’t the only thing to consider, anyone who has flown from UK to Australia, or any other long haul flight will tell you that melatonin or no melatonin, you end up sleeping at 3pm to 1am and haven’t a clue what’s going on. This is where our friend genetics comes into play.

Originally discovered in fruit flies, the use of genetic expression to regulate the body clock has been found in many organisms, including mammals (and yes, that means us). The mechanism itself is remarkable in its simplicity and it goes something like this:

Inside your cells there is DNA kept inside a nucleus. In this instance the DNA is transcribed to produce a protein (which is all DNA ever does). This protein is produced constantly until it reaches a certain concentration. Once it reaches this concentration is binds onto the DNA which stops DNA expression. No DNA expression means no protein. So eventually the protein breaks down and when the levels are low, the DNA is then able to start producing protein again and the cycle continues. This cycle is how your cells tell the time. By knowing how many cycles there are in a day, the cell is able to regulate it’s processes to certain times of the day.

To look at the process itself (without the jargon) lets look at this analogy. Let’s say you bake cookies for a bakery. You bake as many cookies as you can, until they are everywhere, eventually the manager comes and tells you to stop (before you drown in sugary, chocolatey goodness). Eventually you start selling the cookies and suddenly there are only a few left. That’s when the manager tells you to cook more, and the cycle starts again. Now, lets say that this cycle (make cookies>get told to stop> run out> make more cookies) takes 24 hours. Now you know that every cycle you do takes a day, and you can also tell roughly (given the cycle is consistent) what time of day it is depending on where in the cycle you are.

So these cells located in the Suprachiasmatic nucleus (SCN) control your “body clock” and when you get jet-lag it’s because they are working to their own cycle, if you change the pattern of the day (like making it day when you body thinks it should be night), it takes a few days for your body to adjust. This hows that it is both melatonin and gene expression that control your body clock. The clock genes take light levels into account regarding the fine tuning of the cycle.

This topic is vast, and with ever improving technologies looking into cellular interaction and gene expression, it wont be long before we know even more about sleep patterns and circadian rhythms. Here are a few brief “what about”s that cropped up in my mind whilst writing this.

Travelling West to East
Studies have shown that jet-lag is worse for people travelling West to East. One theory about why this is regards the fact that travelling from West to east shortens the day, so you lose hours. This means that when you try to sleep, your body isn’t ready to sleep yet, because it is still stuck in the old cycle. Travelling from East to West actually lengthens the day, so when you arrive you will probably feel more tired earlier, and therefore have little trouble sleeping.

LOUD NOISES!
Why do I, like many other people, hate loud noises in the morning? Well, from my brief research, the internet doesn’t seem to know. At least from a scientific point of view. I suppose it goes without saying, if your still all doped up on melatonin, you probably want to go back to bed, and loud noises are the last thing you want to hear!

Land of the midnight sun,
If you go far enough north, you will reach countries which experience a tough problem. During the summer, these countries experience “Midnight Sun” where the Sun doesn’t set. This means constant  daylight. The opposite is true in the winter, where there is no sun, for days on end. The effects of this on circadian rhythms appears to be quite detrimental. However, there appears to be little information about how humans in these countries have adapted to cope with these conditions (beyond using artificial means that is).

Summary
Circadian rhythms are amazing, I find it’s because with all our technology and intelligence we forget that we are animals, and we are still controlled by biological processes, even when we don’t know it. Research into circadian rhythms is ongoing, and has serious implications for the future. Some studies have suggested that administering drugs at the right point of the circadian cycle can dramatically increase their effectiveness. When we are asleep, our bodies repair themselves and fight infection, so administering drugs when we are at this “repair” stage of our cycle could prove advantageous.

If you want to learn about how genetic expression works, or you didn’t understand the jargon but would like to, check out my science tuition blog.
If you would like to read the (not at all sciency) rant that inspired this article visit my rants blog unclesamsrants.tumblr.com

Any questions or comments? Tweet me @CuriousSamJC

Sources:
http://www2.gi.alaska.edu/ScienceForum/ASF12/1261.html
http://www.healthcentral.com/sleep-disorders/c/5954/48235/ticking/2
http://www.bmj.com/content/317/7174/1704.full#ref-7

  1. curioussam posted this