Category: Light + Health

Rethinking Exposure to Saturated Colored Light

In the most recent issue of Architectural Lighting, LRC Director Dr. Mariana Figueiro explains how red and blue light can be a means of increasing daytime alertness and nighttime sleep….

In the most recent issue of Architectural Lighting, LRC Director Dr. Mariana Figueiro explains how red and blue light can be a means of increasing daytime alertness and nighttime sleep.

While tunable lighting systems provide a dynamic lighting solution that create an aesthetically pleasing environment for users, when it comes to circadian-effective lighting, layers of saturated colored lights delivered at the plane of the cornea, rather than white light coming from the ceiling, may provide a more energy-efficient, comfortable, cost-effective, and aesthetically pleasing design solution.

Check it out here.

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LRC Study Evaluates the Blue-Light Hazard From Solid-State Lighting

The increasing popularity of LED technology has raised concerns about retinal damage via a mechanism known as blue-light hazard. Research conducted by the Lighting Research Center demonstrated in a majority of cases LED lighting does not present a greater risk of blue-light hazard than traditional sources such as incandescent.

LED technology has ignited widespread interest in the ways that lighting can offer benefits to people, including improved visibility at night, enhanced perceptions of brightness and security, and spectral tuning for management of circadian rhythms. Yet, as illustrated in a recent report from the American Medical Association (AMA), the increasing popularity of LED lighting is also raising new questions and reviving older concerns about unwanted impacts of these light sources, such as light pollution, discomfort glare, circadian disruption, and retinal damage via a mechanism known as blue-light hazard.

A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute takes a practical, quantitative approach to evaluating light sources for blue-light hazard. Results of the study are published in the International Journal of Occupational Safety and Ergonomics, in an article titled, “Evaluating the Blue-Light Hazard from Solid State Lighting.”

In the study, LRC researchers John Bullough, Andrew Bierman and Mark Rea evaluate the spectral radiant power characteristics of incandescent, fluorescent, LED and daylight sources in terms of current blue-light hazard calculation procedures from the Illuminating Engineering Society and the Commission Internationale de l´Éclairage. The paper provides comparative data to allow meaningful and quantitative comparisons among light sources commonly experienced indoors and outdoors. Particular attention is given to use cases that could potentially affect blue-light hazard.

The study results showed that in the majority of use cases, LEDs do not exhibit greater risk for blue-light hazard than other light sources, including incandescent. LEDs present no special concerns for blue-light hazard over other common light sources in typical use cases because our natural photophobic responses, such as squinting and averting the gaze, limit exposure to bright light. Where photophobic responses might not occur, such as during eye surgery or with premature infants, caution is needed.

Some organizations, such as the AMA, have advised against using LEDs with correlated CCT exceeding 3000K, however, the LRC study found that avoiding blue-light hazard is primarily related to controlling the radiance of light sources, and much less related to spectral distribution, particularly when expressed in terms of CCT.

The LRC study authors note that CCT should not be used as a metric for characterizing the potential for blue-light hazard, citing the fact that an incandescent filament at 2856K within a clear bulb is associated with a greater risk for blue-light hazard than any white LED source, including one of 6500K. The spectral radiance distribution must be known to estimate blue-light hazard, particularly for those cases where photophobic responses might not occur. In these cases, and indeed for general lighting applications, the study authors recommend the use of lenses, baffles, and diffusers to mitigate glare as the primary methods for reducing the risk of blue-light hazard.

Click here to learn more.

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Lighting Patterns for Healthy Buildings Website Expanded to Include Designs for the Healthcare Environment

The Lighting Research Center has expanded its Lighting Patterns for Healthy Buildings website to include designs for the healthcare environment. The website provides lighting patterns, utilizing circadian stimulus (CS) as the primary design component, for three distinct healthcare environments and the needs of their respective end-users: the shiftwork environment, the NICU, and patient rooms.

To meet the ongoing needs of the patients, hospitals must operate 24 hours per day, 365 days per year, which places tremendous strain on the healthcare staff. Lighting can be used to promote circadian entrainment in various populations as well as promote alertness in healthcare staff working both at night and during the day, yet many lighting professionals are unsure of the best way to incorporate these advances in the science of lighting into their designs. To address this issue, the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute has expanded its Lighting Patterns for Healthy Buildings website to include designs for the healthcare environment.

The website provides lighting patterns, utilizing circadian stimulus (CS) as the primary design component, for three distinct healthcare environments and the needs of their respective end-users: the shiftwork environment, the NICU, and patient rooms.

The project is sponsored by the Light and Health Alliance, which includes Acuity Brands; Cree; Current, powered by GE; Ketra; OSRAM; Philips Lighting; and USAI Lighting.

Click here to learn more.

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Jim Brodrick on Tunable Lighting in a Healthcare Environment

Among the changes taking place in healthcare is a trend in hospitals toward designing larger, single-patient suites that consist of a bedroom and bathroom, rather than the traditional shared rooms. A recently completed DOE-funded R&D project carried out by Philips Lighting Research North America sought to redefine lighting for healthcare patient suites by developing an innovative LED lighting system that not only was 40% more energy-efficient than traditional fluorescent incumbent technologies, but also met all of the visual and non-visual needs of patients, caregivers, and visitors while improving the overall patient experience.

Republication of Postings from the U.S. Department of Energy (DOE) Solid-State Lighting Program

by Jim Brodrick, SSL Program Manager, U.S. Department of Energy

Among the changes taking place in healthcare is a trend in hospitals toward designing larger, single-patient suites that consist of a bedroom and bathroom, rather than the traditional shared rooms. A recently completed DOE-funded R&D project carried out by Philips Lighting Research North America sought to redefine lighting for healthcare patient suites by developing an innovative LED lighting system that not only was 40% more energy-efficient than traditional fluorescent incumbent technologies, but also met all of the visual and non-visual needs of patients, caregivers, and visitors while improving the overall patient experience.

The system of more than 10 luminaires was comprised of state-of-the-art multichannel LED platforms and Power over Ethernet drivers, along with control technologies that provided spectral tuning and became part of an intelligent connected lighting system. Complex and nuanced software was written to set behaviors for a variety of lighting scenes in the patient suite throughout the course of a 24-hour day, including a dynamic tunable-white program, three color-changing automatic programs that simulated sunrise-to-sunset palettes, and an amber night-lighting system that offered visual cues for postural stability to minimize the risk of falls. All programs were designed to provide visual comfort for all occupants, enable critical task performance for staff, support patients’ circadian rhythms, and allow override via manual controls. In addition to spectral tuning, the system makes use of occupancy, daylight, and user controls, with intuitive user-control interfaces for patient, family, and caregivers.

Four independent color channels make it possible for the lighting system to produce a wide range of tunable-color and tunable-white combinations. When the system is operated in tunable-white mode, it provides CRIs ranging between 80 and 85, with CCTs that can be tuned from 2700K-6500K. The advanced controls enable the system to give patients and staff a very different lighting experience, not only adjusting the lighting intensity based on the availability of outside light from the windows when appropriate, but also adjusting the CCT of the luminaire located directly above the bed, and adjusting the color points of the luminaires located around the bed’s perimeter, over the course of the day. These CCTs change from warm in the morning to cool at midday and back to warm in the evening. When the bathroom lights are turned on the middle of the night, their output increases gradually in order to let the patient’s eyes adjust. With all of this functionality combined into a complete solution, the lighting system uses 40% less energy compared to incumbent fluorescent systems.

At a full-scale mockup at Philips’ lab in Cambridge, MA, the lighting system was found to meet visual criteria (confirmed by calculations, simulations, and in situ measurements) as well as non-visual criteria (confirmed by in situ measurements of spectral power distribution and illuminance, and calculations of circadian stimulus levels). Additionally, human-factor evaluations were conducted with eight healthcare professionals, who represented a range of job functions. The overall response to the lighting system was positive, with requests to pilot it at multiple healthcare facilities in recognition of its energy efficiency and value to patient and staff well-being, and unanimous agreement that a tunable lighting system is desirable in a patient room.

Like the RTI/Finelite advanced classroom lighting project that was the subject of a recent Posting, this project illustrates how thinking outside the box and taking a system-wide approach to solve an application problem resulted in a wide range of benefits for those who use the space.

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Solemma to Present Circadian Lighting Design Software at DIVA Day 2017

Solemma is working with sleep scientists at the Alertness CRC in Australian to develop circadian lighting design software geared to architects and lighting professionals. Called ALFA, the software will be demonstrated as a prototype at DIVA Day 2017 on October 27 at the University of California – Berkeley.

Solemma is working with sleep scientists at the Alertness CRC in Australian to develop circadian lighting design software geared to architects and lighting professionals. Called ALFA, the software will be demonstrated as a prototype at DIVA Day 2017 on October 27 at the University of California – Berkeley.

Click here to learn more.

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LRC Releases New Version of Circadian Stimulus Calculator with Expanded Functionality

The Lighting Research Center has released a new version of its free, open-access circadian stimulus (CS) calculator to help lighting professionals select light sources and light levels that will increase…

The Lighting Research Center has released a new version of its free, open-access circadian stimulus (CS) calculator to help lighting professionals select light sources and light levels that will increase the potential for circadian-effective light exposure in architectural spaces.

The new calculator provides additional functions not included in the original version, including the ability to calculate CS levels in rooms with multiple light sources; and combine pre-loaded SPDs from the calculator dropdown and user-supplied SPDs to provide one CS measurement and a single relative SPD.

Lighting professionals can use the CS calculator to compare the effectiveness of various light sources for stimulating the circadian system. The CS calculator utilizes the CS metric, a measure of how one-hour exposure to a light source of a certain SPD and light level stimulates the human circadian system, as measured by acute melatonin suppression.

Click here to learn more and download the calculator.

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Willmorth Challenges Humancentric Lighting

Lumenique’s Kevin Willmorth recently published a blog post questioning the use of the term “humancentric lighting” and raising concerns about how it is being marketed and applied. Without mincing words,…

Lumenique’s Kevin Willmorth recently published a blog post questioning the use of the term “humancentric lighting” and raising concerns about how it is being marketed and applied.

Without mincing words, his post begins:

I do not use, like, or support, the term “Human-Centric Lighting” or HCL, and the marketing of it. Nor am I convinced the bullish marketing of the term makes it any more attractive or legitimate. The term has been tagged onto so many crack-pot claims, unsupported promises, and misapplication of hand-selected, overly simplified misleading single-line extractions from legitimate studies, and anecdotal claims by unqualified “experts” – that it has become nothing more than an extension of the now discredited “Full Spectrum” marketing that has plagued lighting for decades.

The confusion of white light tuning for lighting color effect has now been bolted to human-centric lighting, as more and more marketers rush to stake a claim on this populist movement. I am weary of the numerous “studies” supporting claims, that are nothing more than simple biased surveys of lighting customers, with no effort to remove the Hawthorne Effect, or other bias, that I no longer believe any of them present any meaningful data worth wasting time considering.

He goes on to talk about abuses, what research is telling us now, and that our advancing understanding of the relationship between lighting and health may necessitate new expertise and possibly even a new profession.

Click here to check it out.

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IES Responds to AMA Outdoor Lighting Recommendations

In 2016, the American Medical Association (AMA) announced guidelines encouraging restrictions on the spectral properties of outdoor and roadway lighting, based on CSAPH Report 2-A-16 from their Council on Science…

In 2016, the American Medical Association (AMA) announced guidelines encouraging restrictions on the spectral properties of outdoor and roadway lighting, based on CSAPH Report 2-A-16 from their Council on Science and Public Health.

The Illuminating Engineering Society recently completed a review of the report and guidelines and issued Position Statement PS-09-17, joining with the International Association of Lighting Designers (IALD). IES approached AMA to revisit the guidelines and has stated it will continue to work with AMA to address its concerns.

From PS-09-17:

“The IES respectfully disagrees with the 2016 AMA Policy H-135.927 Statement 2 and the first sentence of Statement 3 specific to limitations on spectral content for outdoor area and roadway lighting. We want to emphasize, that while the principal motivators for the AMA report are understandable, the CSAPH 2-A-16 report filed as background for these statements does not provide sufficient evidence to substantiate these statements, and a more comprehensive analysis of the public health impacts of outdoor and roadway lighting should be considered prior to adopting policies that could have a negative effect on the safety of drivers and pedestrians.”

And:

“The IES also disagrees with 2016 AMA Policy H-135.927 on the basis that Correlated Color Temperature (CCT) is inadequate for the purpose of evaluating possible health outcomes; and that the recommendations target only one component of light exposure (spectral composition) of what are well known and established multi-variable inputs to light dosing that affect sleep disruption, including the quantity of light at the retina of the eye and the duration of exposure to that light … The upper CCT limit of 3000 K contained in AMA Policy H-135.927 lacks scientific foundation and does not assure the public of any certainty of health benefit or risk avoidance.”

Click here to check out the full IES position statement.

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LRC Study Finds Robust Morning Light Improves Sleep and Mood, Lowers Stress in Office Workers

A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute found that office workers who receive a robust dose of circadian-effective light in the morning, from electric…

A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute found that office workers who receive a robust dose of circadian-effective light in the morning, from electric lighting or daylight, experience better sleep and lower levels of depression and stress, than those who spend their mornings in dim or low light levels.

The LRC research team, led by Dr. Mariana Figueiro, professor and director of the LRC’s Light and Health program, investigated the connection between circadian stimulus (CS), a measure of light’s impact on the circadian system, and sleep, depression, and stress in office workers.

The study included 109 participants at five office buildings managed by the U.S. General Services Administration (GSA). Sites included the GSA Central Office in Washington, D.C.; the Edith Green-Wendell Wyatt Federal Building in Portland, Oregon; the Federal Center South Building 1202 in Seattle, Washington; the Wayne N. Aspinall Federal Building and U.S. Courthouse in Grand Junction, Colorado; and the GSA Regional Office Building in Washington, D.C.

Each study participant wore a Daysimeter, a research tool developed by the LRC in 2004, and used in frequent studies to measure the amount of CS a person actually receives, along with their activity patterns. In the present study, each participant was asked to wear the Daysimeter as a pendant for seven consecutive days during data collection periods in winter, between December and February, and again in summer, between late May and August. Data collection was conducted between 2014 and 2016.

LRC researchers collected data on the participants’ sleep and mood using five questionnaires: the Center for Epidemiologic Studies Depression Scale (CES-D), the Perceived Stress Scale (PSS-10), the Pittsburgh Sleep Quality Index (PSQI), the Positive and Negative Affect Schedule (PANAS), and the Patient-Reported Outcomes Measurement Information System (PROMIS) Sleep Disturbance (SD). Participants were also asked to keep a sleep log of bedtimes and wake times, sleep latency, quality of sleep, and any naps taken.

Dr. Figueiro and her team found that office workers receiving a morning CS of at least 0.3, regardless of source (electric lighting and/or daylight), exhibited greater circadian entrainment, were able to fall asleep more quickly at bedtime, and experienced better quality sleep than those receiving a morning CS of 0.15 or less. CS, the calculated effectiveness of light’s impact on the circadian system, ranges from 0.1, the threshold for circadian system activation, to 0.7, response saturation.

Participants who received high CS (at least 0.3) in the morning were able to fall asleep faster at bedtime than those receiving low CS (0.15 or less), and this association was even stronger in the winter months. At bedtime, participants receiving low CS lay in bed for approximately 45 minutes before they could actually fall asleep, which can lead to reduced sleep duration for those with a fixed wake time.

Participants who received high CS in the morning reported lower levels of stress than those receiving low CS, and this finding was consistent during both summer and winter.

While receiving high CS in the morning is hypothetically the most beneficial for entrainment, participants receiving high CS during the entire workday (8:00 a.m. to 5:00 p.m.) experienced better sleep quality and felt less depressed compared to those receiving low CS.

The CS metric has been successfully applied to quantify lighting interventions in many other laboratory and field studies. In the laboratory, CS was used to predict melatonin suppression from self-luminous devices, and in the field, CS was used to predict entrainment in U.S. Navy submariners, and sleep quality and mood in persons with Alzheimer’s disease living in long-term care facilities.

“Our study shows that exposure to high CS during the day, particularly in the morning, is associated with better overall sleep quality and mood scores than exposure to low CS,” said Figueiro. “The present results are a first step toward promoting the adoption of new, more meaningful metrics for field research, providing new ways to measure and quantify circadian-effective light.”

“We are supporting this type of research so we can learn more about the connections between lighting and health,” said Bryan Steverson with GSA. “The data from this research will help support our efforts in developing new lighting practices that can optimize health benefits for federal employees working in our federal buildings.”

Along with Figueiro, co-authors of the study include Bryan Steverson, Judith Heerwagen, and Kevin Kampschroer of the GSA. LRC co-authors include Mark Rea, Kassandra Gonzales, Barbara Plitnick, and Claudia Hunter.

The present study is the first to measure personal circadian light exposure in office workers using a device calibrated to measure circadian-effective light. It is also the first to directly relate circadian-effective light measures to mood, stress, and sleep outcomes.

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LRC Offers Circadian Calculator Tool

I wrote this news piece for the May issue of tED Magazine. Reprinted with permission. The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute recently released a circadian stimulus (CS)…

I wrote this news piece for the May issue of tED Magazine. Reprinted with permission.

The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute recently released a circadian stimulus (CS) calculator. Based on the CS metric, this tool can aid lighting professionals to select light sources and light levels that will increase the potential for effective circadian light exposure in buildings.

Lighting and health is emerging as a significant lighting trend. While a lot of conversation is happening around tunable-white lighting, color spectrum is only part of the story. When specifying lighting for the circadian system, light level, spectrum, timing and duration of exposure must all be factored, in addition to previous light exposure, or photic history.

The CS metric is based on an LRC model of how the retina in the eye converts light stimulation into neural signals for the body’s circadian system. “Lighting for the circadian system employs lighting design objectives that differ from those typically used in traditional architectural lighting design, and therefore requires metrics that differ from those currently used by lighting designers,” says Professor Mariana Figueiro, Light and Health Program Director at the LRC.

The metric centers on determining weighted spectral irradiance distribution of the light incidence at the eye’s cornea, or circadian light (CLA). From this distribution it is then possible to calculate CS, which expresses CLA’s effectiveness from threshold (CS = 0.1) to saturation (CS = 0.7).

Exposure to a CS of 0.3 or greater at the eye, for at least one hour in the early part of the day, is effective for stimulating the circadian system and is associated with better sleep and improved behavior and mood.

In an October 2016 article in LD+A, the Illuminating Engineering Society’s magazine, Figueiro and other LRC researchers point to several ways in which designers can deliver prescribed amounts of CS:

• Request the spectral power distribution (SPD) of light sources as this information is more revealing than correlated color temperature (CCT). Light sources with a higher CCT (5000-6500K) generally provide higher CS, but this is not always true.
• Design for vertical (at the eye) not just horizontal (at the workplane) light levels and use luminaires that provide the best horizontal to vertical light level ratio. LRC evaluated a variety of luminaires and found that a direct-indirect optic provides the best ratio. Other solutions include luminous workstation panels and task lighting that offer vertical brightness.
• Light level and spectrum work together. Lower light levels generally produce lower CS values unless compensated by an SPD that delivers more power at shorter wavelengths (cooler light source). Figueiro points out that when designing for an average workplane light level of 30 footcandles (fc), the researchers found that a 6000K source was needed to achieve the target CS threshold of 0.3. A 4500K source for a workplane light level of 40 fc.

Figueiro advises that the design should also consider light exposure all day, who will be using the space, and layering the light to deliver lighting that is both functional and capable of circadian stimulation.

To use the CS calculator, designers should formulate a base condition by evaluating the space using the calculator and software such as AGi32. The design can later be fine-tuned by gain using the CS calculator, while also accommodating IES recommendations, energy codes and owner requirements.

The development of the CLA and CS metrics and calculator is potentially exciting for the lighting industry. With metrics and tools based on scientific research, the industry can begin developing and vetting practical design concepts aimed at stimulating a circadian response.

The CS calculator can be downloaded free at LRC.RPI.edu/programs/lightHealth/index.asp.

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