The Impact of LED Lighting on Human Circadian Rhythms

Maintaining a healthy circadian rhythm is crucial for our overall well-being. The circadian rhythm, often referred to as the body's internal clock, regulates sleep-wake cycles, hormone release, and other vital bodily functions. In recent years, the widespread adoption of LED lighting has raised concerns about its potential impact on circadian rhythms. This article explores the effects of LED lighting on human circadian rhythms, drawing on recent research.

Circadian rhythms are approximately 24-hour cycles that are driven by the brain's suprachiasmatic nucleus (SCN) and are influenced by external cues, primarily light and darkness. Natural light exposure during the day and darkness at night help synchronise these rhythms to the Earth's 24-hour light-dark cycle. Disruptions to this cycle can lead to various health issues, including sleep disorders, depression, and metabolic problems.

LED (Light Emitting Diode) lighting has become ubiquitous due to its energy efficiency and long lifespan. However, the spectral composition of LED lights, particularly their blue light content, has been shown to affect circadian rhythms. Blue light, which is prevalent in LED lighting, is known to suppress melatonin production, a hormone that regulates sleep.

Research has demonstrated that exposure to blue-enriched LED lighting in the evening can significantly suppress melatonin production, leading to delayed sleep onset and reduced sleep quality. A study published in the journal Energy and Buildings found that blue light exposure from LED lights can delay melatonin production by up to 90 minutes, disrupting the natural sleep-wake cycle.

Additionally, a disrupted circadian rhythm has been found to affect cognitive function and mood. The University of Oxford reported that individuals with misaligned circadian rhythms due to inappropriate lighting experienced decreased cognitive performance and increased symptoms of depression. This is particularly concerning for shift workers and those who spend extended periods under artificial lighting.

Chronic disruption of circadian rhythms has been linked to long-term health issues, with research indicating a link with an increased risk of cancer, metabolic disorders, and cardiovascular diseases. This underscores the importance of considering the spectral quality of lighting in both residential and occupational settings.

How can a commercial environment utilise LEDs and still support staff well-being?

To mitigate the negative effects of LED lighting on circadian rhythms, several strategies can be employed:

• Use of Warm-White LEDs: Opting for warm-white LEDs with reduced blue light content can help minimise melatonin suppression and support healthier sleep patterns.

• Dynamic Lighting Systems: Implementing lighting systems that adjust colour temperature and intensity throughout the day can better align with natural circadian rhythms. For example, cooler, blue-enriched light during the day and warmer light in the evening.

• Limiting Evening Exposure: Reducing exposure to blue-enriched LED lighting in the evening, particularly in bedrooms and living spaces, can help maintain natural circadian rhythms.

The impact of LED lighting on human circadian rhythms is a critical consideration in modern lighting design. While LEDs offer significant energy savings and longevity, their spectral composition can disrupt natural sleep-wake cycles and lead to various health issues. By understanding these effects and implementing appropriate lighting strategies, we can mitigate the negative impacts and promote healthier living environments.

For a free lighting evaluation and to optimise your lighting for better sleep, get in contact today!  

Email: Michael.constantinou@b-enggroup.co.uk

Phone: 07399113788

References:

Zhang, B., Li, J., Liu, M., Li, R., Zhao, K., Guo, L., and Liu, M. "A Study on the Effect of Nighttime Light Intrusion on the Phase Shift of Human Rhythms." Energy and Buildings, 2025. Available at: https://doi.org/10.3390/buildings15060946 [Accessed 8 May 2025] Varma, P., and Rahman, S. A. "Lighting the Path Forward: The Value of Sleep- and Circadian-Informed Lighting Interventions in Shift Work." Sleep, Volume 47, Issue 11, November 2024. Available at: https://doi.org/10.1093/sleep/zsae214 [Accessed 8 May 2025]

Sletten, T. L., Cappuccio, F. P., Davidson, A. J., Van Cauter, E., Rajaratnam, S. M. W., and Scheer, F. A. J. L. "Health Consequences of Circadian Disruption." Sleep, Volume 43, Issue 1, January 2020. Available at: https://doi.org/10.1093/sleep/zsz194 [Accessed 8 May 2025]

Davis, L. K., Bumgarner, J. R., and Fonken, L. K. "Health Effects of Disrupted Circadian Rhythms by Artificial Light at Night." Volume 10, Issue 2, 2023. Available at: https://doi.org/10.1177/23727322231193967 [Accessed 8 May 2025]

Yu, L., Wang, Y., & Jiang, H. (2020). Circadian rhythm disruption induced by alternating light-dark cycle aggravates cardiac remodeling after myocardial infarction through SCN-PVN-SCG-heart sympathetic pathway. JACC: Arrhythmias and Clinical EP, 75(11_Supplement_1), 466.