page_title: Light pollution
section_title: Effects on human health and psychology
hierarchical_section_title: Light pollution / Consequences / Effects on human health and psychology
caption_attribution_description: English: Light pollution in Überwasser in the municipality of Kastelruth in Val Gardena at 1 am. Deutsch: Lichtverschmutzung im Kurort Überwasser (Gemeinde Kastelruth) in Südtirol, wie es sich um ein Uhr nachts am 27. Dezember 2009 bot. Italiano: Inquinamento luminoso a Oltretorrente (comune di Castelrotto) alle ore una di notte del 27 dicembre 2009.
context_page_description: Light pollution is the presence of anthropogenic and artificial light in the night environment. It is exacerbated by excessive, misdirected or obtrusive use of light, but even carefully used light fundamentally alters natural conditions. As a major side-effect of urbanization, it is blamed for compromising health, disrupting ecosystems and spoiling aesthetic environments.
context_section_description: Medical research on the effects of excessive light on the human body suggests that a variety of adverse health effects may be caused by light pollution or excessive light exposure, and some lighting design textbooks use human health as an explicit criterion for proper interior lighting. Health effects of over-illumination or improper spectral composition of light may include: increased headache incidence, worker fatigue, medically defined stress, decrease in sexual function and increase in anxiety. Likewise, animal models have been studied demonstrating unavoidable light to produce adverse effect on mood and anxiety. For those who need to be awake at night, light at night also has an acute effect on alertness and mood.
  In 2007, "shift work that involves circadian disruption" was listed as a probable carcinogen by the World Health Organization's International Agency for Research on Cancer. (IARC Press release No. 180). Multiple studies have documented a correlation between night shift work and the increased incidence of breast and prostate cancer. One study which examined the link between exposure to artificial light at night (ALAN) and levels of breast cancer in South Korea found that regions which had the highest levels of ALAN reported the highest number of cases of breast cancer. Seoul, which had the highest levels of light pollution, had 34.4% more cases of breast cancer than Ganwon-do, which had the lowest levels of light pollution. This suggested a high correlation between ALAN and the prevalence of breast cancer. It was also found that there was no correlation between other types of cancer such as cervical or lung cancer and ALAN levels.
  A more recent discussion (2009), written by Professor Steven Lockley, Harvard Medical School, can be found in the CfDS handbook "Blinded by the Light?". Chapter 4, "Human health implications of light pollution" states that "... light intrusion, even if dim, is likely to have measurable effects on sleep disruption and melatonin suppression. Even if these effects are relatively small from night to night, continuous chronic circadian, sleep and hormonal disruption may have longer-term health risks". The New York Academy of Sciences hosted a meeting in 2009 on Circadian Disruption and Cancer. Red light suppresses melatonin the least.
  In June 2009, the American Medical Association developed a policy in support of control of light pollution. News about the decision emphasized glare as a public health hazard leading to unsafe driving conditions. Especially in the elderly, glare produces loss of contrast, obscuring night vision.
caption: Streetlights at the ski resort Kastelruth in South Tyrol, Italy
exif: {"Image Make": "NIKON CORPORATION", "Image Model": "NIKON D300", "Image Orientation": "Horizontal (normal)", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Elements 5.0 Windows", "Image DateTime": "2010:12:27 18:59:01", "Image WhitePoint": "[313/1000, 329/1000]", "Image PrimaryChromaticities": "[16/25, 33/100, 21/100, 71/100, 3/20, 3/50]", "Image YCbCrCoefficients": "[299/1000, 587/1000, 57/500]", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "372", "GPS GPSVersionID": "[2, 2, 0, 0]", "Image GPSInfo": "1048", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1162", "Thumbnail JPEGInterchangeFormatLength": "2218", "EXIF ExposureTime": "2/5", "EXIF FNumber": "21/5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2009:12:27 00:56:13", "EXIF DateTimeDigitized": "2009:12:27 00:56:13", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "-2", "EXIF MaxApertureValue": "41/10", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire", "EXIF FocalLength": "32", "EXIF SubSecTime": "76", "EXIF SubSecTimeOriginal": "76", "EXIF SubSecTimeDigitized": "76", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "4213", "EXIF ExifImageLength": "2745", "Interoperability InteroperabilityIndex": "R03", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "1016", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CVAPattern": "[0, 2, 0, 2, 0, 1, 1, 2]", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF FocalLengthIn35mmFilm": "48", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Hard", "EXIF SubjectDistanceRange": "0", "EXIF Gamma": "11/5"}