Does Light Impact Our Circadian Rhythm?

Does Light Impact Our Circadian Rhythm

Many people experience insomnia and disrupted circadian rhythms, but have you ever considered changing your light environment? A simple change may help you sleep better. In this article, we will discuss how our nervous system is influenced by light and how it affects our sleep.

Neuroplasticity and Sleep

Neuroplasticity allows us to learn new knowledge, skills, train our brains, and upgrade our bodies. A crucial aspect of neuroplasticity is sleep. When we sleep, our bodies rest, recharge, and reset, enabling us to be more focused, emotionally stable, and motivated when we are awake. So, what factors affect our sleep and why is it significant?

Neuroplasticity and Sleep

This article summarizes insights from Andrew Huberman, an American neuroscientist who has made significant contributions to the fields of brain development, brain plasticity, and neural regeneration and repair. He focuses on the visual system and explains how light affects us in his YouTube channel. One of his videos demonstrates how light impacts our sleep.

According to Huberman, sleep is the incredible period of our lives when we are not conscious, and we are only connected to the processes occurring within our brain and body. Sleep plays a crucial role as it restores our capacity to concentrate, stay alert, and regulate our emotions while we are awake. We cannot discuss wakefulness, focus, motivation, mood, or wellbeing without considering sleep. Our sleep and wake cycles are interdependent, as our actions during wakefulness impact the timing, duration, and quality of our sleep, as well as how we feel upon waking up.

Frequently Used Method in Regulating Circadian Rhythm

Some people refresh themselves with coffee, but caffeine’s effects on sleep vary among individuals, making it unsuitable for everyone.

How to Sleep Well at Night and Be Alert During the Day

Others may take melatonin supplements, but according to Huberman, melatonin is not ideal for everyone either. It is known to suppress the onset of puberty and may help with falling asleep but not staying asleep. If you find melatonin beneficial, it is essential to consult your healthcare professional.

Is There a Safer and More Effective Way to Regulate Sleep?

Yes, there is a more reliable and effective method to regulate sleep: the body’s circadian rhythm. Adenosine, a substance that accumulates during wakefulness, makes us feel sleepy. Our circadian rhythm, a biological instinct that keeps us in a physiological rhythm of approximately 24 hours, controls our endocrine system, metabolism, and more. It influences when we rest, sleep, and wake up.

What Impacts Our Circadian Rhythm?

Our circadian rhythm is primarily affected by two hormones: cortisol and melatonin.

How do Cortisol and Melatonin Impact Our Circadian Rhythm?

When we wake up, our nervous system receives external stimuli and instructs our adrenal glands to secrete cortisol. The hormone cortisol, which is also referred to as the stress hormone, has a beneficial effect on our daily functioning.In the morning, our body releases cortisol and other hormones, allowing us to gradually wake up, activate blood circulation and metabolism, and redirect stored and recovered energy for the day. Our circadian rhythm begins when we wake up, and cortisol levels are activated and start to rise.

How do Cortisol and Melatonin Impact Our Circadian Rhythm

The biological clock in our body sets a countdown of approximately twelve to twenty-four hours. At the end of this countdown, the pineal gland in our brain releases melatonin, a hormone that makes us sleepy and helps us fall asleep.

Our circadian rhythm is a process where cortisol is released in the morning to keep us awake and alert, while melatonin is secreted in the evening, making us sleepy and wanting to rest. Disruption of this natural rhythm has been associated with numerous negative effects, including hair loss, endocrine disorders, insomnia, depression, anxiety, reduced concentration, memory loss, and emotional instability.

Factors That Affect Circadian Rhythms

Although factors like diet and exercise affect circadian rhythms, the most powerful and direct factor is light, especially sunlight. Light can act directly on our nervous system and improve our circadian cycle.

How Light Activates Circadian Rhythms

When we wake up in the morning, one of the first things we do is open our eyes. Upon doing so, light from the environment enters our eyes and reaches the retina. Within our retina, there are special cells called retinal ganglion cells that sense specific properties of light and transmit these signals to our suprachiasmatic nucleus (SCN).

How Light Activates Circadian Rhythms

The SCN, a crucial information hub situated in our brain, is involved in regulating various biological and organ activities throughout our body, including metabolic hormone levels and cellular activity. One of the most important roles of the SCN is to serve as the center of our body’s circadian rhythm, determining when we become awake and when we feel the need to sleep.

Importance of Light in on Our Circadian Rhythms

Light, particularly sunlight, has a more significant impact on our circadian rhythms than factors such as diet and exercise. Sunlight can affect our physiological rhythms a thousand or even ten thousand times more efficiently than other factors. But why is there such a vast difference? It is because retinal ganglion cells, our light sensors, are part of the brain’s nerves themselves. In contrast, when we consume food, it must be digested by the stomach, circulated through the bloodstream, possibly pass through the peripheral nervous system, reach the spinal cord, and finally arrive at the brain.

The light signals our eyes capture are transmitted directly to the SCN, our circadian rhythm center, in just one step and without any intermediaries. Once the SCN receives this signal, it issues instructions that regulate the activities of various organs and cells. The key factor that activates this set of instructions is light, specifically sunlight, such as at sunrise or when the sun’s rays are at a low altitude angle.

One might wonder if sunlight is the only possible activator. For instance, would looking at a mobile phone screen immediately upon waking up in the morning suffice? Or could the sunlight at midday, for those who wake up late, act as an activator of the circadian rhythm? The answer is that it is highly unlikely.

To understand why, stay tuned for our next blog post. Click here for more information.


Written by ——
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
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