8 minute read
Lighting The Way To Better Health
By MARIANA G. FIGUEIRO, PHD
The Light and Health Research Center in 2025
Looking Back
Four years ago, in the middle of the COVID pandemic when vaccines were just becoming available, several of us from the Lighting Research Center at Rensselaer Polytechnic Institute moved to the Icahn School of Medicine at Mount Sinai to establish the Light and Health Research Center (LHRC). It was a bold move, but it was something we simply had to do to continue to be effective in the science of light and health.
Today, we are still going strong and beginning to see some exciting results from our newly completed and ongoing research projects. What follows is a sample of our findings to date and a recap of the LHRC’s research activities since our inaugural article in the June 2021 issue. None of this could have been achieved without our outstanding staff — those who joined from Rensselaer and those who later joined us at Mount Sinai. And, of course, our funders, including various institutes at the National Institutes of Health, the National Institute for Occupational Health and Safety, the American Lighting Association, USAI Lighting, AriBio, the Northwest Energy Efficiency Alliance, the U.S. General Services Administration, BC Hydro, the U.S. Department of Agriculture, the New York Farm Viability Institute, BrainLit, and Vantage Lighting, among others.
As you will see below, our record shows what a great team can accomplish.
Improving cognition in people with mild cognitive impairment and Alzheimer’s disease
We know from our previous studies that a tailored lighting intervention (TLI) delivering circadian-effective light (circadian stimulus >0.3) improves sleep, mood, and behavior in these populations, but what was still unknown was the TLI’s impact on cognition. Using the Alzheimer's Disease Assessment Scale-Cognitive Subscale, which is a neuropsychological assessment to measure the severity of dementia’s cognitive symptoms, we are showing that cognition significantly improves among those receiving a six-month TLI. But it takes time – the effect was only seen after a three-month exposure to the intervention.
Improving sleep and cognition in a cohort of World Trade Center Rescue and Recovery Workers and Volunteers (WTC RRWV)
The brave people who served as WTC RRWV are particularly vulnerable to circadian rhythm disruption and neuroinflammation due to the stress and environmental exposures they experienced during the 9/11 operation. Decades after the event, they continue to show high rates of cognitive impairment and poor sleep quality. We showed that a two-month daily lighting intervention improved sleep and cognition in this population, and that the greater circadian-effective light they were exposed to in the morning, the better their cognitive scores.
Reducing depression
Consistent with our previous work and the research of others, we are showing that a TLI significantly reduces symptoms of depression in various populations, including cancer patients, office workers, and people living with mild cognitive impairment.
Changing the U.S. General Services Administration (GSA) P100 to include circadian-effective light based on UL 24480
Recent work in our long-standing research partnership with the GSA has involved the development of a simple lighting design guideline for delivering circadian-effective light to occupants of the agency’s buildings during the day to support good nighttime sleep. The guideline’s criteria for light received at the occupants’ eyes – a minimum vertical illuminance of at least 400 lx of white light for at least two consecutive hours and a maximum luminance (from luminaires or windows) of less than 8,500 cd/m2 – have been incorporated in the lighting design standards for GSA-owned buildings. Although the new guideline process was not yet in place for a recent field project we conducted with the GSA (see above), the GSA’s goal to create a new building achieving LEED Gold and SITES Silver certification nonetheless employed the UL 24480 guideline developed in concert with LHRC researchers.
Developing new portable luminaires to improve sleep for people at home
We have been working with the American Lighting Association on a program to support its member manufacturers in developing circadian-effective residential lighting. Tentatively named “Better Light, Better Sleep,” when launched, the program will list qualified products that have been photometrically evaluated to provide high levels of glare-free light at the eye in the morning, low levels in the evening, and turn off overnight. The American Lighting Association will be working with lighting showrooms to provide their customers with information about available products and their key features.
Measuring personal, circadian-effective light exposures
Our 24-hour circadian-effective light exposure patterns affect our sleep, health, and productivity. In 2005, our research team developed the Daysimeter, the first calibrated instrument to measure personal circadian-effective light exposure patterns. Over the years we have continuously improved its design, enabling us to accurately measure circadian entrainment and to predict therapeutic light-induced circadian phase changes for better sleep.
Most recently the multi-channel Speck sensor was developed in collaboration with Blue Iris Labs. These calibrated devices are now being used to “coach” individuals with mild cognitive impairment to receive light exposures that can improve the quality of their sleep.
Reducing falls for older adults and hospital patients
Horizontal/vertical nightlights around bathroom doorframes can provide visual cues that promote postural control and stability. One of our recent studies showed a 34% reduction in falls when these lights were used in the rooms of people with Alzheimer’s disease living in assisted living facilities. We are currently collecting data in over 300 rooms to expand on these results. We have also installed these lights in patient rooms at Mount Sinai Hospital and are monitoring falls. The company Filamento has agreed to commercialize this technology.
Reducing skin pigment bias in pulse oximetry
Pulse oximetry is used throughout the medical professions to diagnose hypoxemia (i.e., low blood oxygen levels) in patients to determine if a clinical intervention (e.g., intubation or administration of supplemental oxygen) is necessary. Many recent studies have shown that there is a systematic bias against the accurate diagnosis of hypoxemia in individuals with dark skin. This bias demonstrably increased mortality in this population during the COVID-19 pandemic.
We have shown that the LEDs used in commercially available pulse oximeters cause this bias. There is a systematic shift in the LED spectrum as the light passes through melanin, the epidermal pigment responsible for skin darkening, and this shift upsets a pulse oximeter’s calibration accuracy. We showed that the melanin bias can be eliminated if monochromatic light sources were used in pulse oximeters.
Mitigating risks from pesticide use
Feeding the world is a growing problem that has been accompanied by a growth in the use and development of a wide variety of pesticides to ensure adequate food supplies. Studies have shown that human exposure to some of these materials, either directly through ingestion or indirectly through wind or water dispersion, can be harmful.
We have developed and tested UV-C light delivery systems for a variety of crop types that reduce bacterial and fungal infections that would otherwise compromise yield. These UV-C systems are safe and cost-effective alternatives or adjuncts to pesticide applications, thereby helping to ensure the world is more safely fed.
Improving flashing vehicle lights to increase safety on the road
As automobile drivers, we all have experienced bright flashing lights at night that compromise our ability to see and interpret hazards and people on or near the roadway. Based upon our fundamental knowledge of vision and perception, we have developed lighting systems that alert, inform, and help drivers manage their driving behavior through hazardous roadway environments both night and day. These lighting systems reduce glare and provide intuitive information to drivers about roadside incidents through color and flashing patterns. Not only do they protect drivers, but they also help ensure the safety of police, fire, EMTs, and all others who work in proximity to driving lanes.
Looking forward
As we hope is clear from this brief summary, the LHRC has taken significant strides in the science of light and health over the past four years. Our latest research confirms that light positively impacts human health in ways we had envisioned, and in ways we had only previously imagined. Yet it remains to be seen whether our influence on the scientific community will extend to the lighting industry. We will continue to remain open to forging partnerships with both the lighting industry and designers in the hope that our work will make a positive difference in people’s lives.
To that end, and in closing, listed below are some new projects that we are excited to be part of.
New LHRC projects
Treating sleep disturbances in Long COVID patients with a tailored lighting intervention and oral melatonin
Determining whether delirium in cardiac surgery patients is associated with sleep and circadian rhythms disruption
Using light to improve sleep in Duchenne muscular dystrophy patients
Studying shift work schedules and lighting patterns to minimize circadian disruption in shift workers
Working with AriBio to test a lighting device developed to deliver circadian-effective light to adults with dementia
Exploring the efficacy of a photocatalyst (titanium dioxide) and natural sunlight to control plant diseases
