Light. It seems like just a background element, but in reality, it is the main pilot controlling our health, mood, and energy.
It dictates whether you feel fresh and vital, or if you struggle with autumn apathy, sleepiness, and concentration problems.
Understanding the role of light, especially in the age of screens and round-the-clock activity, is the first step toward better sleep, greater work efficiency (even when supervising a pool!), and saying goodbye to nervousness.
1. Past vs. Present: Why Are We Tired?
Just 100–200 years ago, our circadian cycle was regulated by nature.
When dusk fell, we transitioned to warm light, coming from candles or oil lamps.
This light was characterized by a low colour temperature (around $1800–2000$ Kelvin), which had a minimally negative impact on the production of the sleep hormone.
Moreover, winter was a period of natural, biological rest.
We went to bed earlier and slept longer because our body instinctively reacted to the shortened day.
In the era of the industrial and technological revolution, we lost this rhythm.
Today, we have access to bright, often blue light around the clock.
This causes our brain to be constantly deceived – it thinks it is mid-summer, which disorganizes our natural rhythm.
2. Light and the Biological Clock: Melatonin and Cortisol
Light is the main regulator of our circadian rhythm (internal clock).
Two key hormones are responsible for this:
- Melatonin (the sleep hormone): Produced in the pineal gland, it is released when it gets dark, signalling that it is time to slow down and go to sleep.
- Cortisol (the vitality hormone): Its level rises in the morning under the influence of bright light. It helps us wake up, feel energetic, and get started.
The mismatch between the natural cycle and artificial lighting leads to:
- Chronic fatigue and sleepiness during the day.
- Sleep problems (difficulty falling asleep).
- Seasonal Affective Disorder (SAD): In winter, lack of sunlight can lead to low mood, apathy, and nervousness.
3. Bedroom Mistakes – Darkness is Medicine
The bedroom must be a cave.
Even a small light source can reduce the quality of deep sleep, leading to feeling unrefreshed.
Rules for Night-time Light Hygiene:
- Total Darkness: Use blinds or thick curtains. Street light entering through an uncovered window disrupts melatonin production.
- Night-time Toilet Trips: If you get up at night, DO NOT use bright light. Bright light (especially blue) is an alarm signal for the brain that immediately blocks melatonin. Use a very weak, red or amber light in the bathroom, which has minimal impact on the biological clock.
The Bed is for Sleep Only – This is a key principle!
Lying in bed and looking at a mobile screen or laptop is absolutely unacceptable.
Advice on Reading: Reading in bed with a lamp with warm, yellow light (low colour temperature, e.g., $2100$ K) is better than bright white light, but it is best to read in an armchair. In this way, the bed remains a signal to the brain that this place is solely for sleep and intimacy.
4. Light as a Performance Enhancer and Vitality (Morning Rituals)
If you want to be focused and full of vitality all day, you must reset your biological clock in the morning.
- Morning Signal: After waking up, expose yourself to bright light – preferably sunlight – for 15–30 minutes as soon as possible. This is a strong signal to the brain to start producing cortisol and turn off melatonin.
- My Personal Advice (when lacking sun): If the sun is lacking, e.g., in winter, I believe it is worth turning your face towards a bright lamp or window, even through closed eyelids (absolutely closed!). Our eyelids do not block $100\%$ of the light, and the retina still receives this bright signal, which helps with stimulation.
Light Therapy (Phototherapy)
In cases of severe autumn-winter fatigue or SAD, light therapy is used. It involves daily, morning exposure to very bright, white light with an intensity of around $10,000$ lux (lx) for a specific period. This is a clinically proven method that artificially mimics bright, summer sun, helping to stabilize the circadian rhythm and improve mood. It is worth using if you feel that a walk alone is not enough.
5. Light in the Workplace and Concentration (Lux)
In places requiring constant vigilance and concentration, appropriate lighting is a requirement. Light intensity is measured in lux (lx) – the unit of illuminance per square metre.
- Concentration and Vitality: Bright, well-chosen lighting improves alertness and reaction time.
- Lifeguard Example: For positions requiring high vigilance (e.g., a lifeguard supervising swimmers in a pool), light intensity should be high – recommendations often start from $500$ lx upwards. Working in a poorly lit place leads to eye strain, headaches, and reduced vitality, which is particularly dangerous in this profession.
6. Be Careful with Light: What to Avoid (UV and Retina)
Although light is crucial for life, its extreme intensity is deadly dangerous for our eyes. Our eyes, especially the retina – a delicate layer of light-sensitive cells – are extremely sensitive to a large dose of light energy, especially in the ultraviolet (UV) range.
- Looking at a Welder: Looking at a welding arc (without special protection) is extremely dangerous. It is a very high intensity of light that contains strong UV radiation. It can cause so-called “snow blindness” (inflammation of the conjunctiva and cornea) or, in the worst case, damage the retina, leading to permanent impairment or total loss of sight.
- Looking Through Binoculars at the Sun: Using binoculars or a telescope to look at the sun is extremely dangerous. The optics concentrate all the light energy at one point on the retina, literally burning it. This leads to permanent and irreversible vision loss.
7. Light and Vitamin D: When to Supplement?
Sunlight is also essential for the production of Vitamin D in our skin.
- Production in Summer: In Poland and the northern Scandinavian countries, to effectively produce Vitamin D, we need direct sunlight on uncovered skin (without sunscreen), especially between 10:00 AM and 3:00 PM. About 10–15 minutes daily is sufficient.
- Supplementation in Winter: Due to the low amount of sun in autumn and winter, and the angle of the sun’s rays, Vitamin D production is minimal or zero. Therefore, general supplementation with Vitamin D is recommended during the period from October to April.
SUMMARY: Light is the Pilot of Your Life
Light is not just an element of decoration – it is a crucial, though often ignored, biological signal that regulates our health, energy, and mood. In an era where nature no longer dictates our rhythm, we must consciously control two factors:
- Maximum Brightness in the Morning: To reset the clock, feel vitality, and boost concentration.
- Maximum Darkness in the Evening: To enable melatonin production and ensure deep, restorative sleep.
Remember that even simple changes, such as avoiding your phone in bed and ensuring absolute darkness in the bedroom, have a gigantic impact on the quality of your life.
Use light wisely!
