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research on Human Centric Lighting by
design one lighting design 

A New Approach

A healthy human circadian rhythm depends on the production of melatonin at night, triggered by the absence of sunlight, as well as the depletion of melatonin in the morning, triggered by the presence of sunlight. Our modern work and life habits have us inside and viewing screens, inhibiting our natural circadian rhythms regulating us. Spending our days indoors means our bodies don’t suppress melatonin enough, leading to sleepiness and lack of focus. This is solvable through Human Centric environmental lighting designed to emit 4000K to 6500K color temperature at a brightness of at least 2,500 Lux for at least one hour before midday, and at similar levels until the sun begins to set.
As the sun sets, we often view screens all the way until we fall asleep. Researchers from the Institute for Ophthalmic Research calculated that even light of 1,000 Lux is enough to stop melatonin production, easily as bright as a laptop or TV. Human centric lighting designed to allow melatonin production before sleeping, emitting dimmer light at no more than a 2800K color temperature allows the natural progression of melatonin to take place in our bodies.


Worsening Sleep Habits

CDC doctors in Atlanta have demonstrated a 31% increase in self-reporting adults sleeping for less than 6 hours between 1985 and 2012. (1) National Health Interview Survey data taken between 2010 and 2018 shows a 4.7% increase in adults—representing over 15 million Americans—now getting less than 7 hours of sleep. (2) The Covid-19 pandemic has even further proliferated Americans suffering from insomnia, with sleep researchers at the Harvard T.H. Chan School of Public Health recording a 6.8% increase of DSM-defined sleep issues at least three nights a week (3) in patients.

The Role of Light in our Bodies

The work and lifestyles that have become common within the last 10 to 25 years are often detrimental to our circadian rhythms. Our natural “clock” coordinating our bodily functions, moods, and above all our sleep cycle is innate and has evolved in us for thousands upon thousands of years. Humans require melatonin at night to sleep, triggered by the lack of sunlight, but equally, we require sunlight during the day to suppress melatonin. Staying out of the sun during the day means our melatonin doesn’t suppress enough, while looking at screens at night spikes melatonin levels; the opposite of what should normally happen. As published in the Wiley Journal of Biophotonics, sufficient exposure to blue light, the color temperature of the midday sun, is necessary to suppresses melatonin, (4) “a hormone produced by the pineal gland to promote alertness and cognitive performance during the day.” (5) Without the influence of artificial light, our bodies naturally take the cues of the sunlight for triggering our sleep hormones. After the sun sets, melatonin is secreted and allows a gradual slow-down of our bodily functions preparing us for sleep over the course of 4 to 6.5 hours. (6)

Screens and Sleep

An experiment was conducted at the University of Haifa, in which participants viewed screens for two hours before going to bed, but where half of the participants’ screens were modified to give off only warm light. Participants who viewed unmodified blue-light emitting screens took 16 minutes longer, on average, to fall asleep as well as exhibiting reduced melatonin levels and interrupted REM sleep. (7,8) It is also important to recognize that not only the absence of blue light at night promotes proper sleep and wellbeing, but also the presence of blue light during the day. Research published in the Molecular Vision Journal about the effect of blue light emphasizes that “With age, the lens [of the human eye] becomes more yellowish, and thus, the spectrum of blue light transmission dramatically decreases through the years. It is suspected that one reason older individuals experience sleep problems is the lack of blue light during the daytime.” (9)


We Need Daytime Blue Light

Equally important as melatonin production at night is melatonin suppression during the day in order to make us feel alert and attain the maximum level of coordination and cognitive function. While looking at blue-light emitting electronic device screens up to 2 hours before bedtime has been proven to reduce melatonin levels, (10) the light emitted from screens is not enough on its own to provide proper melatonin suppression during the day. As published in the Journal of Biophotonics, researchers found an environmental brightness of over 2,500 Lux reduced melatonin levels to a proper daytime amount. (11) Additionally, it was concluded that an exposure to light blue light of 1,000 Lux or greater at night was sufficient to interfere with the normal production of melatonin. (12) Human-centric blue light during the day should imitate the color temperature of sunlight, however it should also recognized that finding time for exposure to actual sunlight needs to be a part of any human-centric lighting plan.


Lighting for Happiness

Further supporting the effectiveness of the blue light component of human-centric lighting are “SAD lights.” SAD lights designed to treat Seasonal Affective Disorder, a pattern of major recurrent depression episodes which result from short days and cold weather, appearing in the late fall and winter months. Doctors working on the Mood and Anxiety Program at the University Of Maryland School of Medicine in Baltimore wrote a report titled “Short exposure to light treatment improves depression scores in patients with seasonal affective disorder,” finding that “a significant immediate reduction of depression scores with light treatment can be identified after 20 minutes and reaches the maximum at 40 minutes, with no additional benefit at 60 minutes.” (13) The researchers used the standard SAD Light brightness level recommended by the Mayo Clinic of 10,000 Lux.



1. Ford, Earl S et al. “Trends in Self-Reported Sleep Duration among US Adults from 1985 to 2012.” Sleep vol. 38,5 829-32. 1 May. 2015, doi:10.5665/sleep.4684.

2. Khubchandani, J., Price, J.H. Short Sleep Duration in Working American Adults, 2010–2018. J Community Health 45, 219–227 (2020).

3. Sleep Problems Becoming Risk Factor As Pandemic Continues.Clea Simon - T.H. Chan School of Public Health, Harvard University. April 2020.

4. Wahl S, Engelhardt M, Schaupp P, Lappe C, Ivanov IV. The inner clock-Blue light sets the human rhythm. J Biophotonics. 2019 Dec;12(12):e201900102. doi: 10.1002/jbio.201900102. Epub 2019 Sep 2. PMID: 31433569; PMCID: PMC7065627.

5. Ibid.

6. Ibid.

7. University of Haifa. "Blue light emitted by screens damages our sleep, study suggests." ScienceDaily. ScienceDaily, 22 August 2017. <>.

8. A. Green et al. Evening light exposure to computer screens disrupts human sleep, biological rhythms, and attention abilities. Chronobiology International. Vol. 34, May 26, 2017, p. 855. doi: 10.1080/07420528.2017.1324878.

9. Tosini G, Ferguson I, Tsubota K. Effects of blue light on the circadian system and eye physiology. Mol Vis. 2016 Jan 24;22:61-72. PMID: 26900325; PMCID: PMC4734149.

10. A. Green et al, 2017.

11. Wahl et al, 2019.

12. Ibid.

13. Virk, Gagan et al. “Short exposure to light treatment improves depression scores in patients with seasonal affective disorder: A brief report.” International journal on disability and human development : IJDHD vol. 8,3 (2009): 283-286. doi:10.1901/jaba.2009.8-283.

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