This document discusses the relationship between lighting and human health and wellbeing. It covers how light impacts circadian rhythms and melatonin production, which are linked to health issues like cancer, cognitive decline, and sleep disorders. Certain lighting characteristics like spectrum, timing, duration and flicker frequency can disrupt circadian rhythms. Design considerations are needed for lighting in offices, tunnels and other environments to minimize health risks from light exposure. More research is still needed to better understand light's impact on the human body and provide guidance for lighting professionals.

1. Lighting, Health and Wellbeing Walking the Tightrope Jonathan Green MSLL AMILP eLight Solutions Ltd

7. Circadian Rhythms From "The Body Clock Guide to Better Health" by Michael Smolensky and Lynne Lamberg; Henry Holt and Company.

16. Tunnel Lighting The design of tunnel lighting requires careful consideration. It is well documented that frequencies between 10 and 60 Hz or 10 and 60 flashes per second can trigger seizures in those susceptible. In others it can cause headaches and eyestrain .

19. Tunnel Lighting A1 (M) Hatfield Tunnel – Known for causing Epileptic Seizures Speed (mph) Distance per second (m) Spacing to simulate 2.5Hz (m) Spacing to simulate 18Hz (m) Spacing to simulate 60Hz (m) 30 13.41 5.36 0.75 0.22 40 17.88 7.15 0.99 0.30 50 22.35 8.94 1.24 0.37 60 26.82 10.73 1.49 0.45 70 31.29 12.52 1.74 0.52

20. Conclusions A J Wilkins, Nanno-Smith I, Slater A I and Bedocs L “Fluorescent lighting, headaches and eyestrain”, in LRT Vol 21 (1) 11-18 (1989). Various trends in interior lighting practice and their consequences for health and efficiency (A J Wilkins) Trend Consequences Away from … .And towards For Health For Efficiency 38mm diameter halophosphate fluorescent lamps with 50Hz ballast High-frequency ballasts Good Good Dimmable ballast Good if flicker free Good Narrow band tri-phosphor lamps Possible bad if 50Hz ballast Marginal 26mm lamps Marginal Good High-pressure sources Possibly bad Good Incandescent lighting Compact fluorescent Bad if 50Hz ballast Good Tungsten Tungsten-halogen Bad if high UV otherwise good Good Array of down-lighting luminaires on ceiling forming dazzle pattern Irregular array Good None Multiple point sources Bad if glaring or high UV Bad if incandescent Up-lighting Bad if 50Hz ballast otherwise good Possibly bad Constant lighting Daylight controls Unknown Good Occupancy sensors Unknown Good Increased use of daylight Good Good

26. Lighting, Health and Wellbeing Walking the Tightrope Jonathan Green MSLL AMILP eLight Solutions Ltd