Circadian Rhythms at Work: How Natural Light Affects Our Health and Energy
Ergolain
2026.02.02
Have you ever wondered why a morning walk or a workday spent near a window helps you feel more alert, focused, and even happier? This is no coincidence. Our bodies operate according to an internal clock—our circadian rhythms—which are directly influenced by light.
Modern offices are often designed with functionality, aesthetics, or energy efficiency in mind, yet one essential element is frequently overlooked: the quality of light and its impact on employees’ biological rhythms. Office design and lighting that ignore the effects of natural light can contribute to low energy levels, sleep disturbances, reduced concentration, and even poorer emotional well-being among employees.
In this article, we will take a closer look at how circadian rhythms influence our work, which types of light are most beneficial at different times of the day, and how to design a workplace that supports energy and well-being rather than causing fatigue.
What Are Circadian Rhythms and Why Are They Important in the Workplace?
Circadian rhythms are approximately 24-hour biological cycles that regulate many of the body’s physiological functions, including sleep and wakefulness, body temperature, hormone production, digestion, immune response, and even psychological well-being.
The most important regulator of circadian rhythms is light. Light reaching the retina sends signals to the brain, influencing the production of hormones such as melatonin (the sleep hormone) and cortisol (the alertness hormone). When light exposure does not align with the natural day–night cycle, circadian rhythms become disrupted.
Modern work environments—especially in large cities and business centers—often lack sufficient natural daylight. Even in offices with windows, many workstations are located far from them, in interior zones where natural light is minimal or absent. Prolonged exposure to such environments can lead to:
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Chronic fatigue and reduced work performance;
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Shortened or poor-quality sleep;
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Hormonal imbalance;
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Weakened immune system;
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Increased irritability or feelings of anxiety.
The Impact of Light on Hormonal Balance and Sleep Quality
Our bodies respond to light as the primary “time cue.” When light—especially light containing blue wavelengths (450–480 nm)—reaches the retina, the brain reduces the production of melatonin, the hormone responsible for sleepiness. At the same time, cortisol—the “alertness hormone”—is released, promoting energy, improving concentration, and supporting emotional stability.
Melatonin is naturally produced in the evening as light levels decrease. However, exposure to blue-spectrum light in the evening (for example, from computers, smartphones, or LED lighting) suppresses melatonin production and disrupts sleep. This leads to shorter deep sleep phases and longer time needed to fall asleep.
Cortisol levels should be high in the morning, but poorly planned lighting can disrupt this natural rhythm, potentially resulting in chronic stress, fatigue, or lack of motivation. A well-designed lighting cycle helps maintain hormonal balance and supports overall health.
Differences Between Natural, LED, and Artificial Light in Supporting Circadian Rhythms
Not all light affects our biological clocks in the same way. The main differences between natural light, LED lighting, and traditional artificial light lie in their spectrum, intensity, and ability to change throughout the day.
Natural light provides a full light spectrum whose intensity and color temperature shift over the course of the day. Morning light is brighter and cooler, while evening light is softer and warmer. These natural variations help our bodies stay aligned with daily rhythms. Natural light also improves visual comfort, reduces eye strain, and its positive effects on overall well-being and productivity have been confirmed by numerous studies.
LED lighting, depending on its quality, can be either beneficial or potentially harmful. Standard LED fixtures and bulbs often emit a strong blue light component, which can disrupt melatonin production—especially in the evening. However, next-generation LED systems with dynamic spectrum capabilities can mimic natural daylight rhythms by providing cooler, stimulating light in the morning and warmer, calming light in the evening.
Fluorescent lighting, still widely used in older office buildings, often produces flicker, has an uneven light spectrum, and negatively affects both visual comfort and concentration. It is not designed to support circadian rhythms and frequently contributes to eye strain, headaches, and general fatigue.
In office planning, the quality of light is becoming increasingly important—not just the quantity. It is no longer only about how much light we receive, but how that light source interacts with our biology.
Morning Light or Evening Light – When Are Employees Most Productive?
Circadian rhythms influence our mental and physical state at different times of the day. Morning light is one of the most important stimulators of activity—it not only helps us wake up but also activates cognitive functions such as attention, decision-making, and creativity.
Research shows that cortisol levels peak around 8 a.m., and exposure to light at this time further enhances alertness. Employees who receive sufficient morning light tend to feel more energized and motivated. This is why it is important to design workspaces—especially areas that require focus—so they receive morning or early afternoon light.
Evening light, by contrast, should be softer and less stimulating. When employees are exposed to intense blue light in the evening—particularly from screens—the body is “tricked” into thinking it is still daytime. This can interfere with relaxation, recovery, and the ability to fall asleep. Even if the workday ends around 5–6 p.m., lighting during this time should be less stimulating to support the body’s natural transition into a restful state.
Offices that plan lighting according to the time of day—for example, by using automated lighting systems that adjust color temperature—help employees remain productive while also supporting a healthy and balanced end to the workday.
Natural light
Provides a full spectrum that dynamically changes throughout the day. It is the most optimal light source for supporting healthy circadian rhythms.
LED lighting
Can be aligned with circadian rhythms when using tunable white or circadian lighting technologies.
Standard artificial lighting
Fluorescent lighting often provides a limited imitation of the natural light spectrum and can negatively affect sleep rhythms when used intensively late in the day.
Designing Workspaces Around Light Rhythms: Window Placement and Dynamic Lighting
The most effective way to support circadian rhythms is to design office spaces so that as much natural light as possible reaches workstations:
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Use glass partitions instead of opaque walls;
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Position workstations closer to windows;
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Implement automated lighting systems that adjust intensity and color temperature throughout the day;
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Integrate sensors that regulate indoor lighting based on outdoor daylight levels.
Studies show that employees working in environments with dynamic lighting experience lower stress levels, regain focus more quickly after breaks, and are even less likely to fall ill. As a result, design solutions that integrate light responsive to the time of day into furniture, ceilings, or the overall space are becoming increasingly important in creating health-oriented office environments.
Expert Recommendations and Recent Research
Scientists are increasingly exploring the impact of light on health and work performance. Here are some key insights from recent research:
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A study published in the Journal of Clinical Sleep Medicine found that people working in spaces with natural daylight slept an average of 46 minutes longer and experienced better sleep quality than those working in enclosed, windowless environments.
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Daylight and Productivity – A Field Study showed that employees working near windows or in spaces with dynamic lighting completed 10–15% more work per day compared to colleagues without such lighting conditions.
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The International Commission on Illumination (CIE) recommends planning lighting in alignment with circadian rhythms, particularly in offices, schools, and healthcare facilities.
Circadian rhythms are not just a scientific term—they are one of the key foundations of health, productivity, and employee well-being. Well-planned lighting is not a luxury, but a necessity for organizations that aim to support their people while improving business performance.
Light shapes our energy levels, mood, and overall health. Investments in natural daylight and dynamic lighting solutions pay off through reduced absenteeism, higher productivity, and a stronger sense of connection between employees and their organization.
Ergolain