Table of Contents

    Topic review

    Light and Health

    Submitted by: Oluwapelumi Osibona

    Definition

    Light is important for visual performance and safety, and also plays a vital role in regulating human physiological functions. Poor housing is an important determinant of poor health. One key aspect of housing quality is lighting.

    1. Introduction

    The right to adequate housing is a recognized international human right [1]. The World Health Organisation (WHO) defines healthy housing as one that encourages a state of complete physical, mental and social well-being [2]. People living in inadequate housing are at greater risk of ill health [3][4][5] and inadequate housing conditions are one of the main drivers of health inequalities [2]. Adequate housing is commonly assessed based on housing quality [4][5] which encompasses a wide variety of factors including: crowding and home safety, mould and dampness; temperature and humidity; ventilation and insulation; sanitation; indoor air and noise pollution; radon, asbestos and lead exposure; and lighting [2][4]. Many housing quality factors co-exist within the home, placing occupants at a greater risk of multiple health problems. Housing quality is associated with different health outcomes including developmental, chronic and acute conditions [5][6]. Many housing quality factors are widely studied, for example, mould and dampness [7]; crowding [8]; and lead exposure [5]. Others, however, are understudied despite their potential to impact health. One of the less studied housing quality factors is lighting in the home.

    Adequate lighting is needed for visual performance and safety, and to reduce falls and injuries. Light is also highly essential for health and well-being [9][10][11] through the regulation of bodily functions [12]. Light plays an important role in the function of the nervous and endocrine systems and the secretion of hormones such as melatonin. Melatonin is released by the pineal gland in a 24-h cycle according to how much light is received, regulating the body’s circadian rhythm. In regular sleep-wake cycles, the hormone is highest at night in the dark promoting healthy sleep and lowest during daylight promoting alertness. Disruption to these rhythms caused by a lack of daylight exposure during the day and exposure to bright lights during the night constitutes as improper light exposure which affects health [9][13].

    The importance of light on health is further demonstrated through its therapeutic effects. Symptoms of seasonal affective disorder and other types of depression have been shown to be effectively reduced by both natural and artificial light therapy [14][15][16][17]. Before the discovery of antibiotics, sunlight played a significant role in infection control and preventing the spread of disease in buildings [18][19]. Even today, forms of artificial light are effectively being used in hospital settings to reduce infection transmission [20][21].

    Lighting within the home encompasses different types of light. For instance, homes may be illuminated by natural light through windows and supplemented with artificial light sources during the day, with artificial lighting continuing into the night. As such, there is a need to understand the impact of the various types of lighting in the home on the health of residents. A limited number of systematic reviews have previously explored the impact of lighting on the elderly [22] and the effects of sunlight [23] and light at night [24] on health in certain settings such as care homes. A systematic review that synthesises the evidence of health impacts from different types of lighting in the home is lacking.

    2. Impact of Lighting in the Home on Health

    This systematic review synthesised the existing evidence on links between lighting in the home and health. Though limited in number, the available studies evaluated a range of lighting types (natural light, artificial light and light at night) across twenty-two specific health outcomes. Of the twenty-eight studies included in this review, twenty-five studies observed an association of lighting exposure on at least one health outcome; five of these studies investigated natural light, ten artificial light and ten light at night.

    2.1. Natural Light

    In general, the included studies showed positive associations of natural light exposure and improved health across all health domains (physical, mental and sleep health). Adequate natural light at home has been found to be protective for various health outcomes including tuberculosis, leprosy, depression, mood, falls and sleep. These findings are in line with previous studies conducted in settings other than the home, including offices and hospitals. For instance, in offices, evidence suggests workers with less sunlight exposure have worse self-reported sleep quality [25] and mood [26]. Three systematic reviews focusing on hospital settings identified positive effects on depression in patients with diagnosed depressive illnesses attributable to increased sunlight exposure [27][28][29]. Findings also suggest that exposure to sunlight can improve sleep amongst all hospital in-patients [27][29].

    Our systematic review also identified protective effects of natural light with respect to infectious diseases, possibly due to sunlight’s ability to kill bacteria [30]. Ultraviolet light might act as a natural disinfectant, by weakening and damaging bacteria, causing mutations that limit their ability to reproduce and survive [31]. This disinfectant effect has been found to persists via indirect sunlight exposure through glass [18][32] and windows in homes [33].

    2.2. Artificial Light

    Studies included under the artificial light category used a diverse range of methods to measure exposure to artificial lighting. Methods varied from different sources of artificial lighting (e.g., fuel based, electric, and solar), different electrical lighting equipment (e.g., light bulbs, LED), the adequacy of the lighting available and adjustments to existing electrical lighting (e.g., provision of additional lamps to the living room), all of which showed an impact on health. The majority of studies focused on differential effects on health due to different sources of artificial lighting in the home. There is clear evidence that use of fuel based light sources negatively impact health. In the developing world, 860 million people lack access to electricity [34], as such fuel-based lighting is the common method to illuminate the home. Our review included five studies which evaluated fuel-based lighting compared to electric/solar lighting which were carried out in LMICs. Of those, four showed that individuals using fuel-based lighting compared to electric or solar lighting are more likely to suffer from respiratory diseases and burns. This is consistent with a comprehensive review by Mills et al. on the health impacts of fuel-based lighting [35][36]. Studies have shown that fuel-based indoor lighting choices significantly contribute to the level of indoor air pollution [37]. Fuel based lighting releases particulate matter, volatile organic compounds and other harmful pollutants when burned, and inhalation of these particles into the lungs results in respiratory disease such as acute respiratory lung infections and lung cancer [38][39][40], especially in homes with poor ventilation.

    Burns are one of the top causes of non-fatal injury in children [41]. The use of fuel-based lighting sources can result in burn injuries, for example via overturned kerosene lamps, with a significant proportion of burns occurring amongst children. The placement of lamps is, therefore, an important consideration.

    The type of electric lighting (bulb type and colour temperature) in the home can also impact health. One of the studies on light bulb types included in this review [42] reported worse sleep quality for a light bulb versus LED lighting. It is worth noting, this study did not classify what specific light-bulb types were considered under “light bulb”. However, in Japan, where the study took place, this term is often used to reflect incandescent light bulb [43].

    Only one study reported on colour temperature. Worsened sleep quality but lower daytime anxiety levels were reported when exposed to cooler lights compared to warmer light during the 12-week cross-over study [44]. Light naturally contains a spectrum of colours. The light falling on the eye has an important role in regulating the circadian rhythm. Melanopsin, a photoreceptor in the eye, responds to rich blue light and signals the suppression of melatonin [45]. Sunlight has lower wavelengths during the day corresponding with a bluer light [46]. This exposure to daylight helps to stay alert, while evening exposure to light bulbs containing high levels of blue light signals processes affecting melatonin release and negatively impact sleep [9][47][48]. However, in the study only overhead lights in communal areas (lounge and dining room) were adjusted, and although only residents that frequented these areas were eligible, participants were not be exposed to the intervention in the evening upon returning to their bedroom [44].

    2.3. Light at Night

    Effects of light at night were generally consistently associated with the analysed health outcomes. The majority of the evidence came from the HEIJO-KYO cohort. Results consistently showed high levels of indoor light at night was associated with negative health outcomes (including sleep and metabolic disorders such as obesity, diabetes and dyslipidaemia). The studies conducted on the HEIJO-KYO cohort were of good quality with rigorous methodology, including objective measures of evening and bedroom night-time light intensity with a light meter. Although these results are restricted to a sub-population of home-dwelling Japanese elders, they are in line with the findings of another review [24]. Cho et al. reviewed the effects of artificial light at night across the general population and identified that chronic light at night exposure could negatively impact sleep and other physiological functions [24]. Their review, however, incorporated studies using satellite imagery to measure the outdoor night-time light level. Studies using this measurement method were not eligible for inclusion in our systematic review as it lacks consideration for individual level factors, like window covering practices with blinds and location of the bedroom in relation to streetlights, and as such is not always reliable to represent an individual’s exposure to light within the home [49][50]. Nonetheless, there is still further evidence available supporting the negative impact of light at night within the home on health and sleep in particular [22][47][51][52]. A clear biological explanation for this association exists. Bright light during the night is ill-timed, causing disruptive effects on the circadian rhythm, through suppression of melatonin and subsequently affecting sleep and other metabolic processes [53]. Although this systematic review, sought to evaluate the effect of lighting in the home on melatonin itself in addition to all health outcomes, no studies evaluating the effects of lighting in the home with melatonin were identified or eligible.

    The entry is from 10.3390/ijerph18020609

    References

    1. UN Office of the High Commissioner for Human Rights (OHCHR); The Right to Adequate Housing; UN HABITAT: Geneva, Switzerland, 2009.
    2. WHO. Housing and Health Guidelines; World Health Organization: Geneva, Switzerland, 2018.
    3. World Health Organisation. Housing and Health Equity. Available online: https://www.who.int/sustainable-development/housing/health-equity/en/ (accessed on 19 April 2020).
    4. Bonnefoy, X. Inadequate housing and health: An overview. Int. J. Environ. Pollut. 2007, 30.
    5. Krieger, J.; Higgins, D.L. Housing and health: Time again for public health action. Am. J. Public Health 2002, 92, 758–768.
    6. Shaw, M. Housing and public health. Annu. Rev. Public Health 2004, 25, 397–418.
    7. Caillaud, D.; Leynaert, B.; Keirsbulck, M.; Nadif, R. Indoor mould exposure, asthma and rhinitis: Findings from systematic reviews and recent longitudinal studies. Eur. Respir. Rev. 2018, 27.
    8. Shannon, H.; Allen, C.; Clark, M.; Dávila, D.; Fletcher-Wood, L.; Gupta, S.; Web Annex, A. Report of the systematic review on the effect of household crowding on health. In WHO Housing and Health Guidelines; World Health Organization: Geneva, Switzerland, 2018.
    9. Van Bommel, W.J.M.; Van den Beld, G.J. Lighting for work: A review of visual and biological effects. Lighting Res. Technol. 2016, 36, 255–266.
    10. Boubekri, M. Daylight, architecture and people’s health. In Environmental Health Risk IV. 11; Brebbia, C.A., Ed.; WIT Press: Southampton, UK, 2007; pp. 53–59.
    11. Christoffersen, J. The importance of light to health and well-being. In Proceedings of the 4th VELUX Daylight Symposium “Daylight in a Human Perspective”, Lausanne, Switzerland, 4–5 May 2011.
    12. Wurtman, R. Biological Implications of Artificial Illumination Illuminating Engineering. In Proceedings of the National Technical Conference of the Illuminating Engineering Society, Phoenix, AZ, USA, 9–12 September 1968; Volume 63, pp. 523–529.
    13. Edwards, L.; Torcellini, P. A Literature Review of the Effects of Natural Light on Building Occupants; Contract No.: NREL/TP-550-30769; National Renewable Energy Laboratory: Golden, CO, USA, 2002.
    14. Perera, S.; Eisen, R.; Bhatt, M.; Bhatnagar, N.; de Souza, R.; Thabane, L.; Samaan, Z. Light therapy for non-seasonal depression: Systematic review and meta-analysis. BJPsych Open 2016, 2, 116–126.
    15. Wirz-Justice, A.; Graw, P.; Kräuchi, K.; Sarrafzadeh, A.; English, J.; Arendt, J.; Sand, L. ‘Natural’ light treatment of seasonal affective disorder. J. Affect. Disord. 1996, 37, 109–120.
    16. Pail, G.; Huf, W.; Pjrek, E.; Winkler, D.; Willeit, M.; Praschak-Rieder, N.; Kasper, S. Bright-light therapy in the treatment of mood disorders. Neuropsychobiology 2011, 64, 152–162.
    17. Golden, R.N.; Gaynes, B.N.; Ekstrom, R.D.; Hamer, R.M.; Jacobsen, F.M.; Suppes, T.; Wisner, K.L.; Nemeroff, C.B. The efficacy of light therapy in the treatment of mood disorders: A review and meta-analysis of the evidence. Am. J. Psychiatry 2005, 162, 656–662.
    18. Hobday, R.A.; Dancer, S.J. Roles of sunlight and natural ventilation for controlling infection: Historical and current perspectives. J. Hosp. Infect. 2013, 84, 271–282.
    19. Nightingale, F. Notes on Nursing: What It Is, and What It Is Not; J.B Lippincott Company: Philadelphia, PA, USA, 1960.
    20. Anderson, D.J.; Chen, L.F.; Weber, D.J.; Moehring, R.W.; Lewis, S.S.; Triplett, P.F.; Blocker, M.; Becherer, P.; Schwab, J.C.; Knelson, L.P.; et al. Enhanced terminal room disinfection and acquisition and infection caused by multidrug-resistant organisms and Clostridium difficile (the Benefits of Enhanced Terminal Room Disinfection study): A cluster-randomised, multicentre, crossover study. Lancet 2017, 389, 805–814.
    21. Anderson, D.J.; Gergen, M.F.; Smathers, E.; Sexton, D.J.; Chen, L.F.; Weber, D.J. Decontamination of targeted pathogens from patient rooms using an automated ultraviolet-C-emitting device. Infect. Control Hosp. Epidemiol. 2013, 34, 466–471.
    22. Lu, X.; Park, N.K.; Ahrentzen, S. Lighting Effects on Older Adults’ Visual and Nonvisual Performance: A Systematic Review. J. Hous. Elder. 2019, 33, 298–324.
    23. Aries, M.B.C.; Aarts, M.P.J.; van Hoof, J. Daylight and health: A review of the evidence and consequences for the built environment. Lighting Res. Technol. 2013, 47, 6–27.
    24. Cho, Y.; Ryu, S.H.; Lee, B.R.; Kim, K.H.; Lee, E.; Choi, J. Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment. Chronobiol. Int. 2015, 32, 1294–1310.
    25. Boubekri, M.; Cheung, I.N.; Reid, K.J.; Wang, C.H.; Zee, P.C. Impact of windows and daylight exposure on overall health and sleep quality of office workers: A case-control pilot study. J. Clin. Sleep Med. 2014, 10, 603–611.
    26. Figueiro, M.G.; Steverson, B.; Heerwagen, J.; Kampschroer, K.; Hunter, C.M.; Gonzales, K.; Plitnick, B.; Rea, M.S. The impact of daytime light exposures on sleep and mood in office workers. Sleep Health 2017, 3, 204–215.
    27. Pennings, E. Hospital Lighting and Patient’s Health; Wageningen University: Wageningen, The Netherlands, 2018.
    28. Strong DTG. Daylight Benefits in Healthcare Buildings. 2014. Available online: http://www.designingbuildings.co.uk/wiki/Daylight_benefits_in_healthcare_buildings (accessed on 13 May 2020).
    29. Joseph, A. Impact of Light on Outcomes in Healthcare Settings; The Center for Health Design: Concord, MA, USA, 2006.
    30. Hockberger, P.E. The discovery of the damaging effect of sunlight on bacteria. J. Photochem. Photobiol. B 2000, 58, 185–191.
    31. Doudney, C.O.; Young, C.S. Ultraviolet Light Induced Mutation and Deoxyribonucleic Acid Replication in Bacteria. Genetics 1962, 47, 1125–1138.
    32. Broadhurst, J.; Hausmann, T.W. Bacterial Destruction through Glass. Am. J. Nurs. 1930, 30.
    33. Fahimipour, A.K.; Hartmann, E.M.; Siemens, A.; Kline, J.; Levin, D.A.; Wilson, H.; Betancourt-Román, C.M.; Brown, G.Z.; Fretz, M.; Northcutt, D.; et al. Daylight exposure modulates bacterial communities associated with household dust. Microbiome 2018, 6, 175.
    34. IEA. SDG7: Data and Projections; Internation Energy Agency: Paris, France, 2019.
    35. Mills, E. Identifying and reducing the health and safety impacts of fuel-based lighting. Energy Sustain. Dev. 2016, 30, 39–50.
    36. Mills, E. Health Impacts of Fuel-Based Lighting; The Lumina Project: Berkeley, CA, USA, 2012.
    37. Muyanja, D.; Allen, J.G.; Vallarino, J.; Valeri, L.; Kakuhikire, B.; Bangsberg, D.R.; Christiani, D.C.; Tsai, A.C.; Lai, P.S. Kerosene lighting contributes to household air pollution in rural Uganda. Indoor Air 2017, 27, 1022–1029.
    38. Smith, K.R.; Samet, J.M.; Romieu, I.; Bruce, N. Indoor air pollution in developing countries and acute lower respiratory infections in children. Thorax 2000, 55, 518–532.
    39. Household Air Pollution and Health Geneva: World Health Organization. 2018. Available online: https://www.who.int/news-room/fact-sheets/detail/household-air-pollution-and-health (accessed on 22 April 2020).
    40. Tran, V.V.; Park, D.; Lee, Y.C. Indoor Air Pollution, Related Human Diseases, and Recent Trends in the Control and Improvement of Indoor Air Quality. Int. J. Environ. Res. Public Health 2020, 17, 2927.
    41. Burns: WHO. 2018. Available online: https://www.who.int/news-room/fact-sheets/detail/burns (accessed on 8 September 2020).
    42. Kayaba, M.; Ihara, T.; Kusaka, H.; Iizuka, S.; Miyamoto, K.; Honda, Y. Association between sleep and residential environments in the summertime in Japan. Sleep Med. 2014, 15, 556–564.
    43. Ahlström, K.; Ahlström, M.; Plummer, A. Jisho.org: Japanese Dictionary. 2020. Available online: https://jisho.org/word/電球 (accessed on 13 May 2020).
    44. Hopkins, S.; Morgan, P.L.; Schlangen, L.J.M.; Williams, P.; Skene, D.J.; Middleton, B. Blue-Enriched Lighting for Older People Living in Care Homes: Effect on Activity, Actigraphic Sleep, Mood and Alertness. Curr. Alzheimer Res. 2017, 14, 1053–1062.
    45. Lucas, R.J.; Peirson, S.N.; Berson, D.M.; Brown, T.M.; Cooper, H.M.; Czeisler, C.A.; Figueiro, M.G.; Gamlin, P.D.; Lockley, S.W.; O’Hagan, J.B.; et al. Measuring and using light in the melanopsin age. Trends Neurosci. 2014, 37, 1–9.
    46. Sliney, D.H. What is light? The visible spectrum and beyond. Eye 2016, 30, 222–229.
    47. Aulsebrook, A.E.; Jones, T.M.; Mulder, R.A.; Lesku, J.A. Impacts of artificial light at night on sleep: A review and prospectus. J. Exp. Zool. Ecol. Integr. Physiol. 2018, 329, 409–418.
    48. Effects on Human Health and the Environment (Fauna and Flora) of Systems Using Light-Emitting Diodes (LEDs); ANSES: Maisons-Alfort, France, 2019.
    49. Rea, M.S.; Brons, J.A.; Figueiro, M.G. Measurements of light at night (LAN) for a sample of female school teachers. Chronobiol. Int. 2011, 28, 673–680.
    50. Huss, A.; van Wel, L.; Bogaards, L.; Vrijkotte, T.; Wolf, L.; Hoek, G.; Vermeulen, R. Shedding Some Light in the Dark-A Comparison of Personal Measurements with Satellite-Based Estimates of Exposure to Light at Night among Children in the Netherlands. Environ. Health Perspect. 2019, 127, 67001.
    51. Dautovich, N.D.; Schreiber, D.R.; Imel, J.L.; Tighe, C.A.; Shoji, K.D.; Cyrus, J.; Bryant, N.; Lisech, A.; O’Brien, C.; Dzierzewski, J.M. A systematic review of the amount and timing of light in association with objective and subjective sleep outcomes in community-dwelling adults. Sleep Health 2019, 5, 31–48.
    52. Caddick, Z.A.; Gregory, K.; Arsintescu, L.; Flynn-Evans, E.E. A review of the environmental parameters necessary for an optimal sleep environment. Build. Environ. 2018, 132, 11–20.
    53. Gooley, J.J.; Chamberlain, K.; Smith, K.A.; Khalsa, S.B.; Rajaratnam, S.M.; Van Reen, E.; Zeitzer, J.M.; Czeisler, C.A.; Lockley, S.W. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J. Clin. Endocrinol. Metab. 2011, 96, E463–E472.
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