Research Insight 01: Circadian lighting

Circadian lighting is tuneable lighting that can alter its colour and intensity. It aims to improve people’s alertness during the day or during working hours using bright light, but to switch to lower brightness, warmer coloured lighting when it is time to relax. Circadian lighting effects on health and wellbeing is a research project jointly funded by the BRE Trust and CIBSE to investigate circadian lighting and its effectiveness and how it should be controlled. This report gives an overview of the work carried out to help identify the best way to control circadian lighting under real-world conditions. It includes key findings from the initial literature review, and summarises the field study and the main results. Key conclusions and tentative recommendations based on the study findings are also provided.

Scope of this publication:

• Summary of literature review
  • Human circadian system
  • Impact of light spectrum on circadian rhythms and performance
  • Circadian disruption and impacts on human health
  • Exposure to daylight in buildings
  • Effects of bright artificial lighting
  • Existing research on circadian/ dynamic/ variable lighting
  • Measures of circadian lighting
• Field study
  • Experimental setup
  • Key findings
• Conclusion and recommendations

Outputs from this project include:

• A workshop held at BRE on 29 September 2016, dicussing the following papers:
  • ‘Human centric lighting in offices’, Dr Bianca van der Zande, Philips Lighting
  • ‘Investigation into the effects of short wavelength light on human alertness in the immediate to short term’, Scott Window, Fowler Martin
  • ‘New measurement toolkit and SI-compliant photoreceptor weighted light intensities’, Dr Katharina Wulff, Oxford University
  • ‘Preliminary findings of literature review on circadian lighting’, Dr Cosmin Ticleanu, BRE
• Literature review
  • Ticleanu, C. (2017). Report describing initial literature review on circadian lighting. BRE Client Report B137170-1001. Watford, BRE, 2017. Available at https://www.cibse.org/knowledge/ knowledgeitems/detail?id=a0q0O00000CF7o9QAD
• Published article
  • Littlefair, P. and Ticleanu, C. (2019). Evaluating dynamic lighting, CIBSE Journal, Health and Wellbeing Special, June 2019, 18-20. Available at https://www.cibsejournal.com/technical/evaluating-dynamiclighting
• Papers for publication
  • Ticleanu, C. and Littlefair, P. Circadian lighting effects on performance and wellbeing – A field study comparison of fixed and variable lighting conditions, Phase 1. Manuscript in preparation for publication.
  • Ticleanu, C. and Littlefair, P. Circadian lighting effects on performance and wellbeing – A field study comparison of fixed and variable lighting conditions, Phase 2. Manuscript in preparation for publication.
  • Littlefair, P. and Ticleanu, C. Daylight data for the effect of natural light on circadian rhythms. Manuscript in preparation for publication.
• Interim reports (unpublished)
  • Ticleanu, C. (2016). Interim report describing initial literature review on circadian lighting and workshop to review key issues. Report B137170-01 for BRE Trust and CIBSE, December 2016.
  • Ticleanu, C. and Littlefair, P. (2017). Circadian lighting; proposals for experimental work. Report B137170-1001 for BRE Trust and CIBSE, February 2017.
  • Ticleanu, C. (2017). Progress report giving update on work to date. Report P108730-1001 for BRE Trust and CIBSE, November 2017.
  • Ticleanu, C. (2018). Interim report giving initial experimental results. Report P108730-1002 for BRE Trust and CIBSE, March 2018.
  • Ticleanu, C. (2018). Progress report giving update on experimental work. Report P108730-1003 for BRE Trust and CIBSE, May 2018.
• Presentations
  • Littlefair, P. (2019). ‘Lighting for circadian rhythms’, paper presented to the BRE Indoor Environment Conference, Watford, 28 February 2019.
  • Ticleanu, C. (2019). ‘Lighting and health & wellbeing’, paper presented to the BRE Wellness and Biophilia Symposium, Watford, 6-7 June 2019.