Exposure to light is crucial for our physical and mental health, as this and future articles in the series will show.
But the timing of that light exposure is also crucial. This tells our body to wake up in the morning, when to poo and the time of day to best focus or be alert. When we’re exposed to light also controls our body temperature, blood pressure, and even chemical reactions in our body.
But how does our body know when it’s time to do all this? And what’s light got to do with it?
What is the body clock, actually?
One of the key roles of light is to re-set our body clock, also known as the circadian clock. This works like an internal oscillator, similar to an actual clock, ticking away as you read this article.
But rather than ticking you can hear, the body clock is a network of genes and proteins that regulate each other. This network sends signals to organs via hormones and the nervous system. These complex loops of interactions and communications have a rhythm of about 24 hours.
In fact, we don’t have one clock, we have trillions of body clocks throughout the body. The central clock is in the hypothalamus region of the brain, and each cell in every organ has its own. These clocks work in concert to help us adapt to the daily cycle of light and dark, aligning our body’s functions with the time of day.
However, our body clock is not precise and works to a rhythm of about 24 hours (24 hours 30 minutes on average). So every morning, the central clock needs to be reset, signalling the start of a new day. This is why light is so important.
The central clock is directly connected to light-sensing cells in our retinas (the back of the eye). This daily re-setting of the body clock with morning light is essential for ensuring our body works well, in sync with our environment.
In parallel, when we eat food also plays a role in re-setting the body clock, but this time the clock in organs other than the brain, such as the liver, kidneys or the gut.
So it’s easy to see how our daily routines are closely linked with our body clocks. And in turn, our body clocks shape how our body works at set times of the day.
What time of day?
Matt Garrow/The Conversation.Adapted from Delos, CC BY
Let’s take a closer look at sleep
The naturally occurring brain hormone melatonin is linked to our central clock and makes us feel sleepy at certain times of day. When it’s light, our body stops making melatonin (its production is inhibited) and we are alert. Closer to bedtime, the hormone is made, then secreted, making us feel drowsy.
Our sleep is also partly controlled by our genes, which are part of our central clock. These genes influence our chronotype – whether we are a “lark” (early riser), “night owl” (late sleeper), or a “dove” (somewhere in between).
But exposure to light at night when we are supposed to be sleeping can have harmful effects. Even dim light from light pollution can impair our heart rate and how we metabolise sugar (glucose), may lead to psychiatric disorders such as depression, anxiety, and bipolar disorder, and increases the overall risk of premature death.
The main reason for these harmful effects is that light “at the wrong time” disturbs the body clock, and these effects are more pronounced for “night owls”.
This “misaligned” exposure to light is also connected to the detrimental health effects we often see in people who work night shifts, such as an increased risk of cancer, diabetes, and heart disease.
How about the gut?
Digestion also follows a circadian rhythm. Muscles in the colon that help move waste are more active during the day and slow down at night.
The most significant increase in colon movement starts at 6.30am. This is one of the reasons why most people feel the urge to poo in the early morning rather than at night.
The gut’s day-night rhythm is a direct result of the action of the gut’s own clock and the central clock (which synchronizes the gut with the rest of the body). It’s also influenced by when we eat.
In the world, human beings are facing various problems. People who are full of greed, anger, and ignorance are seen to be fighting with each other in words and deeds. As the fighting continues, various problems such as civil wars, wars of aggression, and wars of aggression are occurring. As world peace is being destroyed, humans are facing unbearable problems. Innocent children and women are not getting the rights they deserve and deserve. I can't think of one thing every time. What is it? The United Nations. If we look at the responsibilities and duties of the United Nations, I think it is not suitable for solving the problems that are happening in the world today. In fact, the United Nations and the World Security Council, such an organization must rule the world, must be able to give orders, and must have various ways to obey orders. There must be no organization that can influence more than that organization. There should be experts from each country. They can even dominate the superpowers like the US, China, and Britain. Only then will global peace be achieved quickly. Now, if a country with power develops more militarily, economically, or socially than its own country, then powerful countries will jealously seek out enemies and wage war. Or they will attack with fighter jets. In this, innocent people are losing their lives. No one understands the value of a life. You should think about how to achieve global peace by controlling these. If the US continues to be the permanent president of the UN, world peace will never be achieved. If you think carefully, no one sees that they are working for the common good, but for their own benefit, for the benefit of their own country. The permanent president of the UN and the Security Council has rejected this, As a young Rohingya, I have come to realize that only by electing the president and secretary from among the countries in the world through a secret ballot system and governing the world fairly can we achieve global peace. The United Nations and the Security Council are organizations in which any country must govern, give orders, and make them obey their orders. For example, only when a defendant is tried in court can we hold the leaders of the countries in check and control them, can we achieve global peace smoothly. Otherwise, it will not be easy for powerful countries to use various excuses to end this war every year, every year, for the benefit of themselves and their countries. No country's leaders pay any attention to the words of the United Nations and the Security Council. If we look at it in practice, look at the Rohingya issue. Myanmar is a small country. Even that country has been under siege for 8 years. What action can be taken? Why is the UN and the Security Council Powerless? Without such Power, how can the organization bring about global peace? Everyone should think about it. Whether there is a veto or a strong one, all countries in the world can only achieve global peace if they are subject to the UN and the Security Council. Seek peace in the quiet embrace of nature. Peace is an indispensable need of the human race. It is not as if one person can kill another person, and it is as if one country can attack another country, but instead of trying to build peace, we must try to destroy the peace now, and the world is getting hotter and is on the verge of collapse. I especially appeal to all the world experts to urgently try to bring about peace in all parts of the world. Mr, Noor Muhamed Arkhan Rohingya Youth Myanmar
Film and Writing Festival for Comedy. Showcasing best of comedy short films at the FEEDBACK Film Festival. Plus, showcasing best of comedy novels, short stories, poems, screenplays (TV, short, feature) at the festival performed by professional actors.
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