LIGHT- a Friend or Foe?
Recently I have been researching on the non-visual effects of lights (NVEL) and found some scary stuff which I had to share with my readers. However the findings are either theoretical or based on laboratory experiments, informed mostly from epidemiological researches. This post is a extract from of my academic research solely posted with an intention to make my readers aware of the devastating effects lights can create and possible ways to ameliorate them!
Natural day-night-cycle promotes human wellbeing. Daylight exposure is essential to conduct several physiological functions (Roberts 2010). However practically we spend 90% of the time indoors (SynthLight 2004) under static artificial illumination resulting in elongated days and poor day-night contrast (Blask et al 2012). This leads to disruption of human-circadian-rhythm. The finding that breast cancer incidence is highest in industrialized regions where night-light is ubiquitous directed the research of NVEL in buildings (Rea 2002). Considering that natural-lighting modulations are unavoidable within buildings it is necessary to study the NVEL on human-health to avert any negative effects.
Eye detects electromagnetic solar radiations in the range of 380-740nm (Thompson and Hill 2010) called visible radiation or light. Hitherto it was considered that brain receives signals (mostly visual) through ‘rods and cones’. During 1990’s third photoreceptor ‘Intrinsic photosensitive retinal ganglion cell (ipRGC)’was discovered (Graham 2011; Duffy and Czeisler 2009). ipRGC contains ‘melospin’ photo-pigment that conveys non-visual signals via ‘retinohypothalamic-path’ to ‘Suprachiasmatic-nuclei (SCN)’ located in brain. SCN is considered the ‘biological-clock’ and relays information to nervous system that regulates production of different neurohormones and neuropeptides mainly depending on the day-night-cycle and the timing of light-exposure (Roberts 2010).
Circadian-system controls daily and seasonal rhythms (CIE 2003; Roberts 2010; SynthLight 2004). Circadian-rhythm is endogenous. Natural-light aids entrainment of the human-clock which is between 24-25hrs to match with environmental-photoperiod (CIE 2003; Roberts 2010;Duffy and Czeisler 2009; Blask et al 2012; Cromie 1999) hence the presence of daylight or its equivalent within the building is essential for well-being.
Non-visual effects of lights (NVEL) on human-health
Although NVEL is relatively a new study and several areas are still dubious. It is confirmed that light-exposure differing environmental-photoperiod is detrimental to health. For example it causes cancer, cardiovascular disease, metabolic disorders, mental and emotional problems, sleep disorders, depression and mood disorders, gastrointestinal and digestive disorders, affects cognitive functions, immune system and reproductive functions (Blask et al 2012; Bommel 2006; CIE 2003; Circadian-rhythm (2013); Duffy and Czeisler 2009; Lynch 2008a; Morgia et al 2011; Portaluppi et al 2012; Rea 2002; Roberts 2010).
What affects Circadian-response?
Circadian-response is a slow cyclic process (Rea 2002; Blask et al 2012). Phase-shift (delay or advancement) of circadian-rhythm can easily occur if time and intensity of environmental-photoperiod is modified (CIE 2003; Rea 2002; Bieske et al 2012). Bright daylight and low or no nightlight benefits circadian-rhythm. Longer low-level day-time light-exposures due to limited daylight exposure or by use of energy-saving artificial-lighting can suppress melatonin (Rea 2002; Blask et al 2012) while early evening or nightlight-exposure also results in phase-delay (Anderen et al 2012). Constant time-change in light-dark patterns affects circadian-rhythm most (Roberts 2010; Webb 2006).
Such findings imply two things-importance of living in harmony with environmental-photoperiod and influential lighting parameters that affect circadian-response (LPCR). LPCR are interrelated. These include light spectrum, correlated color temperatures, intensity, direction and timing.
Morning daylight has blue-short-wavelength and entrains daily human-circadian-system (Figueiro and Rea 2010). Blue-wavelengths exposure is beneficial at day-time and harmful for night and the opposite is good for night-shift-workers (Roberts 2010). Roberts (2010) pointed at some artificial-lights like incandescent and fluorescent-light that have little or no irradiance at 480nm wavelength and hence safe for night-use. However this reading may be faulty since same lamp type may generate different spectrum reading based on how it is measured (Padfield no-date).
Daylight is uniform, diffused (Zilber 1993; Lynch 2008a; Altomonte 2008) and provides wide spectral irradiance strong at all visible wavelengths (Blask et al (2012). Most artificial-lights are dominated by wavelengths nearing 555nm (Figueiro and Rea 2010). It is hard to mimic natural-light quality even with full-spectrum artificial-light since they have spiky (fluorescent-light) or incremental monotonic irradiance (incandescent-light) wavelengths (Blask et al 2012)
Daylight can achieve best retinal-illumination as compared to artificial-lights (Altomonte 2008 ). Rea (2002); Bieske et al (2012); Roberts (2010) agree that direction of light has an important role in triggering circadian-response. However exact location of non-visual photoreceptors is still not known (CIE 2003).
Daylight is highly dynamic in illuminance as compared to indoor environment (Zilber 1993; CIBSE 2003; Blask et al 2012; Altomonte 2008). Duffy and Czeisler (2009) noted that day-time indoor-lighting is inadequate while Falchi et al (2011) noted that nightlight exposure in an urban setting with artificial-lighting is about 200 times higher compared to environmental-photoperiod, both of which are detrimental to health.
A wide range of illuminance (0.2lux-1000lux) is capable to trigger circadian-response (Bommel 2006; Circadian-rhythm 2013; Rea 2002; Falchi et al 2011; Duffy and Czeisler 2009; Blask et al 2012). Rea (2002) showed time progression also affects sensitivity to nightlight.
Selecting appropriate lights:
Daylight is a sure winner as far as ameliorating NVEL is concerned. Surveys endorse sunlight as a preferred light-source (Lynch 2008a). Benefits of using daylight include substantial energy-saving, low-carbon-emissions, improvement in mood, motivation and productivity (Kjeld Johnsen no-date; Lynch 2008a; SynthLight 2004; Bommel 2006). Daylight in buildings however must be balanced with its visual-effects like uniformity, glare and heat gain. However it is not always possible to use daylight.
Global artificial-light use still comprises of 67% high-energy-consuming incandescent-lamps versus 33% energy-savers within which housing consumes 75% of incandescent-lamps (The Climate group no-date). Compact-fluorescent-lamps and Light-emitting-diodes are thrust globally to reduce energy use and carbon emissions. However these have not been carefully evaluated for NVEL. The research on NVEL is still ongoing and applying partial knowledge can deem incorrect but so is our knowledge of using energy-efficient lamps (for their non-visual effects).
Summary: Lighting aids vision but it can also prove detrimental to human-health if NVEL are ignored. Living in harmony with environmental-photoperiod may leave the circadian-system intact. Daylight is most preferred. Selection of complementary artificial-lights needs consideration of NVEL. The study of NVEL is of special interest while designing spaces for night-shift workers or for people with special needs. Hence application of above learning must result in situational lighting design.
- Altomonte, S. (2008) ‘Daylight for Energy Savings and Psycho-Physiological Well-Being in Sustainable Built Environments’ Journal of Sustainable Development, 1(3), pp.3 [Online] Available at: http://www.ccsenet.org/journal/index.php/jsd/article/view/1198 (Accessed: 7 Feb 2013)
- Anderen. M, Mardaljevic. J and Lockley. SW (2012) ‘A framework of predicting the non-visual effects of day-light- Part 1 Photobiology- based model’ Lighting Research and Technology 44 (1), pp. 37-53 Sage Journals [Online] Available at: http://lrt.sagepub.com/content/44/1/37.abstract (Accessed: 9 Feb 2013)
- Bellia. L, Bisegna. F, Spada. G (2011) ‘Lighting in indoor environments: Visual and non-visual effects of light sources with different spectral power distributions’ Building and Environment 46(10) pp. 1984–1992, Elsevier [Online] Available at: http://www.sciencedirect.com/science/article/pii/S0360132311001004 (Accessed: 1 Feb 2013)
- Bieske. K, Schierz and Vandahl. C (2012) ‘Biological effects of light – Literature overview’ Technical Safety pp.30-35 Chapter: Industrial Lighting on day, Technical University of Ilmenau, Germany [Online] Available at: http://www.m4ssl.npl.co.uk/wp-content/uploads/2012/02/Biological-effects-of-light-%E2%80%93-Literature-overviewEnglish.pdf and http://www.tu-ilmenau.de/lichttechnik/publikationen/ (Accessed: 3 Feb. 2013)
- Blask. D, Brainard. G, Gibbons. R, Lockley. S, Stevens. R and Motta.M (2012), ‘Light Pollution: Adverse Health Effects of Night time Lighting’ American Medical Association, Available at: http://www.atmob.org/library/resources/AMA%20Health%20Effects%20Light%20at%20Night.pdf (Accessed: 4 Feb 2013)
- Bommel (2006) ‘Non-visual biological effect of lighting and the practical meaning for lighting for work’ Applied Ergonomics 37(4), pp. 461–466 Sciencedirect [Online] Available at: http://www.sciencedirect.com/science/article/pii/S0003687006000524 (Accessed: 6 Feb 2013)
- Boyce. PR, Beckstead. JW, Eklund. NH, Strobel. RW, and Rea. MS (1997) ‘Lighting the graveyard shift: the influence of a daylight–simulating skylight on the task performance and mood of night shift workers’ Lighting Research and Technology, 29 (3), pp.105-142 Sage Journals [Online] Available at: http://lrt.sagepub.com/content/29/3/105.abstract (Accessed: 8 Feb 2013)
- Brainard. G, Hanifin. J, Greeson. J, Byrne. B, Glickman. G, Gerner. E and Rollag. M (2001) ‘Action spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor’. Journal of Neuroscience 21(16) pp.6405-6412 Society of Neuroscience [Online] Available at: http://www.jneurosci.org/content/21/16/6405.abstract (Accessed: 5 Feb 2013)
- Brainard and Hanafin (2004), ‘The effects of light on human health and behaviour: relevance to architectural lighting’ CIE Symposium 2004 Light and Health: Non-Visual Effects. Austria 30 September – 2 October 2004, University of Music and Performing Arts Vienna, Austria:CIE pp 2-16 [Online] Available at: http://www.gbv.de/dms/tib-ub-hannover/513349111.pdf (Accessed: 5 Feb 2013)
- Cajochen. C, Zeitzer. JM, Czeisler. CA, and Dijk. DJ (2000) ‘Dose-response relationship for light intensity and ocular and electroencephalographic correlates of human alertness’ Behavioural Brain Research 115 (1), pp.75-83 [Online] Available at: http://www.sciencedirect.com/science/article/pii/S0166432800002369 (Accessed: 3 Feb 2013)
- CIE (2003) International Commission on Illumination- Ocular Lighting Effects on Human Physiology mood and Behaviour [Online] Available at: http://www.elisirlin.com.ar/02_report%20CIE%20ocular%20lighting%20effects%20611.pdf (Accessed: 6 Feb 2013)
- CIBSE (2003) CIBSE Commissioning Code L: Lighting (SLL Commissioning Code L) [Online] Available at: https://www.cibseknowledgeportal.co.uk/component/dynamicdatabase/?layout=publication&revision_id=124&st=Code+of+lighting+part+2 (Accessed: 1 Feb 2013)
- Circadian-rhythm (2013) Wikipedia. Available at: http://en.wikipedia.org/wiki/Circadian_rhythm (Accessed: 10 Feb. 2013)
- Cromie. W (1999) The Harvard university Gazette: Human Biological Clock Set Back an Hour Available at: http://news.harvard.edu/gazette/1999/07.15/bioclock24.html (Accessed: 8 Feb 2013)
- Duffy and Czeisler (2009) ‘Effect of Light on Human Circadian Physiology’ Sleep Med Clin. 4(2), pp. 165–177 National Institute of Healt Public Access [Online] Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717723/pdf/nihms128437.pdf (Accessed: 4 Feb 2013)
- Falchi. F, Cinzano. P, Elvidge.C Keith. D and Haim. A (2011) Journal of Environmental Management, 92(10), pp. 2714–2722 Sciencedirect [Online] Available at: http://www.sciencedirect.com/science/article/pii/S030147971100226X (Accessed: 1 Feb 2013)
- Figueiro and Rea (2010) ‘Lack of short-wavelength light during the school day delays dim light melatonin onset (DLMO) in middle school students’ Neuro Endocrinol Lett, 31(1),pp. 92–96 PMC- US National Library of Medicine [Online] Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3349218/(Accessed: 8 Feb 2013)
- Graham (2011) Webvision: The Organization of the Retina and Visual System Available at: http://webvision.med.utah.edu/book/part-ii-anatomy-and-physiology-of-the-retina/elanopsin-ganglion-cells-a-bit-of-fly-in-the-mammalian-eye/ Accessed: 4 Feb 2013)
- Kjeld Johnsen (no-date)’Natural light ‘Danish Building Research Institute Department of Health and Comfort’ CEM161- References [Online] Available at: http://uelplus.uel.ac.uk (Accessed: 1 Feb. 2013)
- Kozakov R, Franke S and Schöpp. H (2008) ‘Approach to an effective biological spectrum of a light source. The Journal of the Illuminating Engineering Society of North America 4(4) Leukos [Online] Available at: http://www.iesna.org/leukos/Volume4/number4.cfm (Accessed: 7 Feb. 2013)
- Lynch 2008a) ‘Natural Light and Daylighting’ CEM161 [Online] Available at: http://uelplus.uel.ac.uk (Accessed: 1 Feb. 2013)
- Lynch, (2008b) ‘Artificial Lighting’ CEM161 [Online] Available at: http://uelplus.uel.ac.uk (Accessed: 1 Feb. 2013)
- Mills. P,Tomkins. S and Schlangen. L (2007) ‘The effect of high correlated colour temperature office lighting on employee wellbeing and work performance’ Journal of Circadian Rhythms 2007, 5(2) [Online] Available at: http://www.jcircadianrhythms.com/content/5/1/2(Accessed: 2 Feb. 2013)
- Morgia. C, Ross-Cisneros F, Hannibal. J, Montagna. P, Sadun. A and Carelli. V (2011) ‘Melanopsin-expressing retinal ganglion cells: implications for human diseases’ Vision Research 51(2) Sciencedirect [Online] Available at: http://www.sciencedirect.com/science/article/pii/S0042698910003706 (Accessed: 5 Feb. 2013)
- Nabil and Mardaljevic (2005) ‘Useful daylight illuminances: a replacement for daylight factors’ Energy and Buildings, 38 (7) pp. 905-913 [Online] Available at: http://www.sciencedirect.com/science/article/pii/S0378778806000636 (Accessed: 7 Feb. 2013)
- Noguchi. H, Ito. T, Katayama.S, Koyama. E, Morita. T and Sato. M (2004) ‘Effects of bright light exposure in the office’ CIE Symposium 2004 Light and Health: Non-Visual Effects. Austria 30 September – 2 October 2004, University of Music and Performing Arts Vienna, Austria:CIE pp 153–156 [Online] Available at: http://www.gbv.de/dms/tib-ub-hannover/513349111.pdf (Accessed: 5 Feb 2013)
- Padfield (No-date) ‘Measuring and working with different light sources’ The National Gallery Available at:http://research.ng-london.org.uk/scientific/spd/?page=info (Accessed: 8 Feb. 2013)
- Perret Opticians (2012) Colour Vision, Available at: http://www.perret-optic.ch/optometrie/Vision_des_couleurs/vis-couleur_gb.htm (Accessed: 4 Feb 2013)
- Portaluppi. F, Tiseo. R, Smolensky. M, Hermida. R, Ayala. D and Fabbian. F (2012) ‘Circadian rhythms and cardiovascular health’ Sleep Medicine Reviews 16 (2), pp. 151-166, Sciencedirect [Online] Available at: http://www.sciencedirect.com/science/article/pii/S1087079211000554 (Accessed: 5 Feb. 2013)
- Rea (2002) ‘Light-much more than vision’ Light and Human Health: EPRI/LRO 5th International Lighting Research Symposium, Newyork, USA. The Lighting Research Office of the Electric Power Research Institute, pp. 1-15. [Online] Available at: http://www.lrc.rpi.edu/programs/lightHealth/pdf/moreThanVision.pdf (Accessed: 3 Feb. 2013)
- Rea. MS.; Bullough. JD, Bierman. A and Figueiro MG (2006) ‘Implications for White Light Sources of Different Correlated Color Temperatures on human circadian functions’ Commission Internationale d’Eclairage (CIE) 2nd Expert Symposium: Light and Human Health Symposium Proceedings, Ottawa, ON. September 7-8, 2006 pp. 33-38
- Roberts. J (2010) ‘Circadian Rhythm and Human Health’ Photobiological Sciences Online-American Society for Photobiology, [Online] Available at: http://www.photobiology.info/Roberts-CR.html (Accessed: 2 Feb. 2013)
- SynthLight (2004) Available at: http://www.new-learn.info/packages/synthlight/handbook/index.html (Accessed: 3 Feb. 2013)
- Thapan. K, Arendt. J and Skene. D (2001) ‘An action spectrum for melatonin suppression: evidence for a novel non-rod, non-cone photoreceptor system in humans’ Journal of Physiology 535 pp.261-267 [Online] Available at: http://jp.physoc.org/content/535/1/261.full (Accessed: 7 Feb. 2013)
- The Climate group (no-date) LED- Cutting CO2 emissions from global lighting, Available at: http://www.theclimategroup.org/_assets/files/LightSavers-Two-Pager.pdf (Accessed: 1 Feb. 2013)
- Thompson and Hill (2010) ‘Principles of Lighting’ CEM161 [Online] Available at: http://uelplus.uel.ac.uk (Accessed: 1 Feb. 2013)
- (Thompson 2013) ‘Principles of Sunlight and Solar Gain’ CEM161 [Online] Available at: http://uelplus.uel.ac.uk (Accessed: 1 Feb. 2013)
- Webb. A (2006) ‘Considerations for lighting in the built environment: Non-visual effects of light’ Energy and Buildings 38(7) Sciencedirect pp.721–727 [Online] Available at: http://www.sciencedirect.com/science/article/pii/S0378778806000648 (Accessed: 2 Feb. 2013)
- Zilber (1993)’Review of health effects of indoor lighting’ Architronic, Available at: http://corbu2.caed.kent.edu/architronic/v2n3/v2n3.06.html