This is one of those articles that many of you in senior positions will read and grasp that something needs to be done.

And then, do nothing, muttering something along the lines of: “It’s never done us any harm.”

But here’s the uncomfortable truth: the science says otherwise.

"One of the ‘tools of my trade’ is a light meter. Whenever I consult with any type of work or performance environment, I test the indoor light. I see it as a hugely important metric."

Phil Learney - HMN24 Co-Founder

 

When we consider what fuels workplace reliance on caffeine during the day and alcohol at night, most people blame stress, long hours, or a company culture that fosters these habits. But science is pointing to a quieter culprit: the lighting in your office.

Light as Biology, Not Decoration

Light isn’t just about what we see, it’s about how we function.

Specialised retinal cells, known as intrinsically photosensitive retinal ganglion cells (ipRGCs), send light signals directly to the brain’s master clock, the suprachiasmatic nucleus (SCN). This clock regulates daily cycles of dopamine, cortisol, and melatonin, the neurochemicals that govern wakefulness, focus, and sleep (1, 2).

When we spend our days in dim offices and our evenings bathed in harsh artificial light, these cycles slip out of sync. The result? Fatigue, mood instability, and a dangerous reliance on chemical substitutes.

The Stimulant Trap

• Too little blue-rich light during the day reduces natural alertness and dopamine sensitivity. Research shows that exposure to bright, blue-enriched light enhances alertness, stabilises circadian rhythms, and improves cognitive performance (3, 6).

• Workers compensate with coffee, energy drinks, or nicotine, anything to stay switched on.

• Studies link low-light office environments with increased caffeine consumption and reduced performance (2, 7).

Caffeine, in the short term, can mask fatigue. But when it is consumed in excess, as is often the case in chronically under-lit environments, it leads to overstimulation, disrupted sleep, and diminished recovery (12). This creates the conditions for a self-perpetuating cycle of dependency.

The Depressant Trap

• Too much artificial light in the evening, particularly from LED screens and overhead lighting, delays melatonin release and fragments sleep (4, 9).

• To force rest, people turn to alcohol, sedatives, or sleep aids.

• While alcohol can help initiate sleep, it disrupts REM and slow-wave sleep, leading to poorer recovery and next-day fatigue (5).

This means that workers may go to bed earlier after drinking, but they wake up less refreshed. The cycle then swings back to the stimulant side of the equation the following morning.

The Cycle of Dependency

Over time, this pattern becomes self-reinforcing: stimulants by day, depressants by night.

Workers in poorly lit environments consistently report higher stress, burnout, irritability, and depressive symptoms (8, 12). What looks like a lifestyle choice is often a physiological reaction to environmental design.

Work environments with poor daytime lighting (too dim, wrong spectrum) reduce alertness and dopamine sensitivity, while evening overexposure to artificial light delays melatonin. The result: fatigue, poor sleep, and reliance on caffeine or alcohol to compensate.

Why This Matters for Leaders

For senior leaders, this isn’t a trivial detail about office design. It’s about performance, resilience, and risk.

• Productivity: Employees in workplaces with good lighting conditions sleep better, concentrate more effectively, and report higher job satisfaction (10, 11).

• Health costs: Chronic circadian disruption has been linked to mood disorders, metabolic dysfunction, and cardiovascular risk (2, 8). The downstream effect is higher absenteeism and healthcare costs.

• Culture: An office environment that forces workers into cycles of stimulant and depressant use fuels burnout, presenteeism, and turnover.

Breaking the Cycle

The good news is that lighting can be engineered to support biology rather than fight it.

• Dynamic lighting systems that follow the natural progression of daylight, bright and blue-rich in the morning, softer and warmer in the evening, improve mood, restore circadian alignment, and reduce reliance on caffeine and alcohol (10, 11).

• Increasing access to natural daylight or introducing targeted light interventions has been shown to reduce stress and improve workplace performance (13, 6).

• Education and awareness—teaching employees why light matters, helps shift habits around screen use, sleep hygiene, and reliance on chemical “fixes.”

The Takeaway

If your office relies on strip lights, windowless rooms, and screens that glow late into the night, it’s not just uncomfortable, it’s unhealthy.

Poor lighting isn’t simply a design flaw. It’s an environmental driver of drug-like behaviour, pushing people toward caffeine and alcohol to maintain balance.

Lighting isn’t a luxury. It’s a biological necessity. And if we want healthier, more productive workplaces, we need to design with biology in mind, not just aesthetics.

Please drop us an email if you'd like to discuss ways to improve your workplace lighting. 

References

1. Berson, D. M., Dunn, F. A., & Takao, M. (2002). Phototransduction by retinal ganglion cells that set the circadian clock. Science, 295(5557), 1070-1073.

2. Walker, W. H., Walton, J. C., DeVries, A. C., & Nelson, R. J. (2020). Circadian rhythm disruption and mental health. Translational Psychiatry, 10, 28.

3. Chellappa, S. L., Steiner, R., Blattner, P., Oelhafen, P., Götz, T., & Cajochen, C. (2011). Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert? PLoS ONE, 6(1), e16429.

4. Gooley, J. J., Chamberlain, K., Smith, K. A., Khalsa, S. B., Rajaratnam, S. M., Van Reen, E., … & Lockley, S. W. (2011). Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. Journal of Clinical Endocrinology & Metabolism, 96(3), E463-E472.

5. Ebrahim, I. O., Shapiro, C. M., Williams, A. J., & Fenwick, P. B. (2013). Alcohol and sleep I: effects on normal sleep. Alcoholism: Clinical and Experimental Research, 37(4), 539–549.

6. Hirakawa, H., et al. (2025). Light exposure and behavioural health in office workers: associations with stimulant use and mood. Chronobiology International.

7. Vandewalle, G., et al. (2018). Light as a modulator of cognitive brain function. Trends in Cognitive Sciences, 22(5), 422–437.

8. Masullo, A., et al. (2023). Circadian disruption, burnout, and mood disorders in office workers. Occupational Health Science, 7, 215–229.

9. Menculini, G., et al. (2024). Artificial light at night, melatonin suppression, and emotional regulation. Sleep Medicine Reviews, 69, 101944.

10. Karaman, Ö., & Avcı, D. (2022). The effect of dynamic lighting on circadian rhythm and work performance. Lighting Research & Technology, 54(5), 451–467.

11. He, Y., et al. (2023). Dynamic lighting and workplace wellbeing: a systematic review. Journal of Environmental Psychology, 86, 101972.

12. Weerakkody, R., et al. (2025). Occupational lighting, stimulant use, and burnout: a multi-centre study. Occupational Medicine.

13. Turner, K. (2024). Light interventions in occupational settings: impacts on sleep and wellbeing. Frontiers in Psychology, 15, 1275438.