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Light profiles, in photopic illuminance (solid gray, left ordinate scale) and in circadian stimulus (solid black, right ordinate scale) units [37], for two women working in daylighted offices in Troy, NY, USA. Measurements were made continuously starting at 15:00 on 1 December 2005 until 14:30 on 2 December 2005. Also shown are vertical photopic illuminances (dashed black, left ordinate scale) expected from outdoor exposure to a partly cloudy sky at the same location on the same date in open country for a 45° azimuth angle from the sun [26].

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Research Items (54)
... However, the duration of evening light exposure is an important consideration. As a benchmark, 30 minutes of exposure to 30 lux is suggested as the threshold at which light begins to stimulate the circadian system (predicting 15% melatonin suppression) for incandescent lighting exposure in the home among women (79). ...
... Over the past years, several attempts were made to review the impacts of ALAN on human and ecosystems health (e.g., Figueiro et al. 2006;Haim and Zubidat 2015;Bedrosean and Nelson 2017;Wendeu-Foyet and Menegaux 2017;Aulsebrook et al. 2018). However, previous reviews were focused on distinct, often narrow, aspects of ALAN-ecosystem interactions. ...
... To reach this criterion CS, the 6500 K white light source would have required exposure to approximately 42 lx for 3 h; the 2700 K would have required approximately 95 lx for 3 h. In light of the present study results, the proposed melatonin suppression threshold of 30 lx for 30 min for white light, suggested by Figueiro, Rea, and colleagues in various publications ( Bullough et al., 2008, Figueiro et al., 2006b), appears to be an acceptable, if very conservative, recommendation. However, whether < 10 % melatonin suppression can be deemed as a "safe" criterion for light at night is an idea that requires further consideration and additional research. ...
... Even though the absolute sensitivity of the human circadian system has been shown to be affected by not only lighting characteristics (e.g., spectrum) but also the physiological (e.g., age) and behavioral (e.g., photic history) traits of the target population, the threshold criterion of 10% is intended to be conservative and based on the response of the age group with the highest circadian sensitivity (i.e., adolescents). Figueiro et al. (2006b) recommended 30 lux of white light at the cornea, 30 min before bedtime, as a preliminary working threshold for reliably measuring melatonin suppression while cautioning against its broad application due to individual differences between subjects and the spectral power distributions of light sources. A follow-up study partially supported that recommended threshold, demonstrating that a 1-h nighttime exposure to white light (2670 K) at the eye reliably suppressed melatonin by 19% at a level of 200 lux, but not at 60 lux . ...
... Even though the absolute sensitivity of the human circadian system has been shown to be affected by not only lighting characteristics (e.g., spectrum) but also the physiological (e.g., age) and behavioral (e.g., photic history) traits of the target population, the threshold criterion of 10% is intended to be conservative and based on the response of the age group with the highest circadian sensitivity (i.e., adolescents). Figueiro et al. (2006b) recommended 30 lux of white light at the cornea, 30 min before bedtime, as a preliminary working threshold for reliably measuring melatonin suppression while cautioning against its broad application due to individual differences between subjects and the spectral power distributions of light sources. A follow-up study partially supported that recommended threshold, demonstrating that a 1-h nighttime exposure to white light (2670 K) at the eye reliably suppressed melatonin by 19% at a level of 200 lux, but not at 60 lux . ...
... Hatta ıık yo¤unlu¤unun derecesiyle tümör büyüme hızı arasında do¤ru orantının varlı¤ını gösteren çalımalar da bildirilmitir. [17,18] ...
... The model of human circadian phototransduction proposed by Rea et al 19 was used to estimate the circadian stimulus (CS) of the lighting intervention. While melatonin levels were not collected, calculations showed that 300-400 lux (at the cornea) of the high-CCT light would result in at least 50% melatonin suppression for a 1-hour exposure for a young subject, 30 indicating that the light source used in the intervention delivered strong circadian stimulation. Although it is not known whether the CS for circadian entrainment and phase shifting is the same as the CS for acute melatonin suppression, 31 Due to changes in the aging eye, older people are slightly less sensitive to short wavelengths than are young observers for any source of light, but the differential effect can be estimated. ...
... In laboratory studies, melatonin production was not suppressed by polychromatic light intensities below 80 lux (Zeitzer et al., 2000), and suppression has been shown to occur within 30 minutes of light exposure (Bojkowski et al., 1987;Revell & Skene, 2007;Thapan et al., 2001). Comparable thresholds have been reported by other studies (Figueiro et al., 2006a(Figueiro et al., , 2006b. We therefore classified light exposure by the duration of light exposure above 80 lux occurring 30 minutes before each saliva sample (0-30 minutes). ...
... Moreover, light exposure was not significantly associated with either peak melatonin or change in melatonin levels observed between the two shifts. The researchers attributed their study's failure to find melatonin suppression to the fact that the maximum LAN level the nurses experienced was 37.2 lux, which is below the 80-lux level shown to have an effect on melatonin production (Figueiro, Rea, & Bullough, 2006;Zeitzer, Dijk, Kronauer, Brown, & Czeisler, 2000). Dumont, Lanctot, Cadieux-Viau, and Paquet (2012) measured melatonin production and exposure to LAN in a study on the effects of shift work. ...
... In laboratory studies, melatonin production was not suppressed by polychromatic light intensities below 80 lux ( Zeitzer et al., 2000), and suppression has been shown to occur within 30 minutes of light exposure ( Bojkowski et al., 1987;Revell & Skene, 2007;Thapan et al., 2001). Comparable thresholds have been reported by other studies ( Figueiro et al., 2006aFigueiro et al., , 2006b). We therefore classified light exposure by the duration of light exposure above 80 lux occurring 30 minutes before each saliva sample (0-30 minutes). ...