The Photobiological Effects of Electric Light Sources: How Artificial Light “Affects” Life

Plants: The Secrets of Photosynthesis and Photoperiodism

In nature, light is fundamental to plant growth.

The two most critical photobiological processes are:

Photosynthesis: Chlorophyll in green plants absorbs light energy, converting carbon dioxide and water into carbohydrates.

Photoperiodism: Plants determine seasons by day length, thereby regulating rhythms of flowering, growth, or dormancy.

In modern agriculture, both phenomena can be simulated and controlled using artificial light sources. High-pressure discharge lamps are commonly used for greenhouse lighting due to their compact size and minimal light obstruction; fluorescent lamps serve as an ideal alternative when natural sunlight is unavailable. Scientists can even manipulate plant growth patterns by adjusting light spectrum composition—for instance, accelerating flowering or promoting stem and leaf development.

Livestock Farming: Lighting Can Also “Raise Animals”

In animal husbandry, light's impact is equally remarkable. White light at 10–30 lux significantly boosts poultry's annual egg production; low-intensity red light calms birds, facilitating weight gain; ultraviolet light promotes animal health by aiding vitamin D synthesis. In some zoos, “day-night reversal lighting” is even used to regulate animal behavior: dim red light during the day and bright light at night. This encourages nocturnal animals to be active during the day, making them more visible to visitors.

Additionally, violet and ultraviolet light are used in insect traps, attracting insects into the trap through specific wavelengths.

Medical and Health Applications: The Dual Nature of Ultraviolet and Infrared Light

Light's medical applications are diverse. Ultraviolet therapy commonly employs high-pressure mercury lamps, with bulbs specially designed to filter out harmful radiation below 280 nanometers.

Low-dose ultraviolet light (such as that provided by fluorescent lamps) is used for health maintenance and skin therapy.

However, excessive UV exposure can cause skin inflammation, premature aging, and even skin cancer.

Conversely, moderate UV exposure is beneficial: it stimulates vitamin D synthesis in the skin, promotes the production of protective pigments, and enhances UV resistance.

Meanwhile, infrared radiation is readily absorbed by human tissue, providing a warm, soothing sensation that helps alleviate muscle soreness and nerve tension. This makes it a common feature in physical therapy devices.

Conclusion: From Illumination to Life Regulation

Modern light sources are no longer merely tools for “illuminating the world”; they are becoming critical factors influencing life processes in agriculture, animal husbandry, and medicine.

In the future, with advancements in spectral regulation and bio-optics, artificial light sources may truly evolve into a technological means for precisely controlling biological rhythms.

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