Circadian rhythms oscillate at a period close to 24 hours and should be entrained (or synchronized) with the natural 24-hour solar day, essentially telling our bodies to do the right things at the right times. If our rhythms become desynchronized or disrupted by light (or dark) at the wrong time in the circadian cycle, we can experience problems with metabolic and neurobehavioral performance, including sleep. Lighting in the built environment is typically specified to meet the needs of the human visual system (e.g., visibility, comfort), often at the expense of the human circadian system’s needs. The Light for Human Health program strives to better understand the lighting characteristics (i.e., amount, spectrum, timing, duration, and distribution) required for the circadian system and to develop effective applications for maintaining healthy circadian rhythms to improve the symptoms and lives of those living with Alzheimer's disease, depression, jet lag, or sleep disorders. These goals have been at the core of our research team’s efforts for three decades.
Light for Human Health
Adolescents and Classrooms
As they transition into the second decade of life, adolescents’ sleep/wake pattern shifts later into the night and longer into the morning. These later bedtimes frequently involve the use of self-luminous electronic devices, which can further disrupt sleep due to adolescents’ greater sensitivity to light compared to younger children and adults. The Light and Health Research Center conducts research in adolescent populations to promote circadian entrainment and improve the lighted environment in the classroom and at home.
Alertness and Performance
Alertness and task performance are acutely influenced by exposure to light at any time of day or night. Research at the Center focuses on characterizing and specifying light for promoting alertness and performance in a wide range of populations and settings. U.S. Navy submariners, metropolitan railroad dispatchers, and night-shift nurses all have benefitted from research and lighting solutions developed and implemented by the Center’s researchers.
Light at Night
Exposure to light at night adversely affects human physiology and behavior, carrying increased risk for sleep disruption and life-threatening illnesses such as cancer, metabolic disorders, and cardiovascular disease. Lighted environments that promote restful sleep and synchronization of the circadian system can counter these ill effects and are therefore crucial for maintaining health and well-being for people of all ages. We have conducted extensive research on the effects of light at night and developed techniques to improve sleep and health outcomes among older adults, patients and workers in general hospital settings and neonatal intensive care units, and evening workers.
Architectural lighting has traditionally addressed visual performance and the amount of light on the work plane, later focusing on energy efficiency and only recently considering human health outcomes. Our research team has examined sustainable lighting designs that meet energy-use goals while promoting the health and well-being of office workers. We have worked extensively with U.S. government agencies to improve the lighted environment and promote alertness and vitality in office buildings across the country and embassies in northern latitudes.
Older Adults and Elder Care
Tailored lighting interventions can dramatically improve the lives of older adults by promoting postural control and stability; mitigating some symptoms of Alzheimer's disease; improving sleep and mood; and optimizing the aging eye’s visual performance. The Center’s field research addresses these themes in diverse environments and populations, from Alzheimer’s disease patients in assisted living facilities to cognitively intact elders living at home.
Shift work has been linked to poor sleep, chronic metabolic disorders (e.g., cardiovascular disease, diabetes, and obesity), depression, and elevated risk for the occurrence of accidents, especially when workers’ schedules involve working through the night. The Center’s researchers are investigating and developing lighting intervention strategies to promote alertness and reduce health risks in shift workers.
Circadian Stimulus Calculator
The Center has developed a circadian stimulus (CS) calculator to assist lighting professionals in the selection light sources and illuminance levels that will optimize circadian-effective light exposure in architectural spaces.
The Center has conducted multi-year research into healthy workplace lighting for promoting alertness, physical and emotional health, and sleep at home. Funded by the National Institute of Occupational Safety and Health, this web resource provides the latest information lighting for shift workers that will be of interest to health care facility managers, designers, and interested in promoting healthy outcomes through lighting.
Lighting in Federal High-Performance Green Buildings – Reports
In 2013, the U.S. General Services Administration (GSA) awarded a contract to the Light and Health Research Center (LHRC). See full list of related reports.
Lighting for Health and Energy Savings – Guidance Documents
These guidance documents provide recommendations and techniques for designing lighting for health and well-being while minimizing energy use in three applications: offices, K-12 classrooms, and hospital patient rooms.
- Army Research Office
- Blue Iris Labs
- European Commission
- Jim H. McClung Lighting Research Foundation
- National Institute of Diabetes and Digestive and Kidney Diseases
- "Clock modulation in circadian desynchrony induced diabetes and atherovascular disease - mechanisms and interventions” (R01DK128972-02)
- National Cancer Institute
- "Systematic Light Exposure Effects on Circadian Rhythms Entrainment, Inflammation, Neutropenic Fever and Symptom Burden among Multiple Myeloma Patients undergoing Autologous Stem Cell Transplantation“ (1R01CA260961-01A1)
- National Heart, Lung, and Blood Institute
- "Studying 24-hour rhythms of light exposure, alignment with rest-activity cycle, and cardiometabolic health in a nationally representative sample” (1R21HL165369-01)
- National Institute of Neurological Disorders and Stroke
- National Institutes of Health
- “Methodology Issues in a Tailored Light Treatment for Persons with Dementia” (R01AG034157)
- “Light, Metabolic Syndrome and Alzheimer's Disease: A Non-Pharmacological Approach” (R01AG060716)
- “The Long-Term Impact of Light Intervention on Sleep Physiology and Cognition in Mild Cognitive Impairment” (R01AG062288)
- “The Use of Rhythmic Light Therapy to Entrain Gamma Oscillations and the Circadian System in Patients with Alzheimer's Disease and Related Dementias (ADRD)” (R01AG072762)
- “Understanding Circadian Responses to Light in Persons with Mild Cognitive Impairment and Alzheimer's Disease” (R21AG070713)
- National Institute on Aging
- “A Pragmatic Crossover Trial to Test the Effectiveness of a Novel Lighting System to Reduce Nighttime Falls in Persons with Alzheimer’s Disease and Related Dementias” (1R01AG075010-01)
- “Identifying the Long-Term Neurological Effects of COVID-19 Using 7 Tesla Multi-Modal MRI” (1R21NS122389-01)
- Office of Naval Research
- US Department of State
- US General Service Administration, Office of Federal High-Performance Buildings (GS14H17AAC0002)
- Warren Alpert Foundation
Light for Human Health Partners