Tag Archives: Circadian System

Healthy Lighting: Spotlight on Assisted Living

  1. Understanding of Circadian Lighting
    • Circadian light differs from the generally conceived definition of visual light in that it refers to the affect of lighting on the human circadian system, as opposed to light as a stimulus for the human visual systems.
    • Optimal functioning of the circadian timing system is imperative for good health and can be assisted with proper lighting systems. For appropriate designing of lighting and the associated SPD’s, we depend upon the Circadian Stimuli (CS) that each light offers. Simply defined, the light output or the light levels are not as important in this situation, as the CS factor of each light.
    • Humans have developed an endogenous timing system that optimally synchronizes physiology and behavior (e.g. rest/activity cycles)
    • The timing of our daily biological functions are organized and orchestrated by the master circadian clock. This is hosted by the suprachiasmatic nuclei (SCN) in the hypothalamus
    • The SCN orchestrates circadian rhythms in behavior and physiology via endocrine and neural pathways.
    • The Circadian System (“circa”, around; “dies”, day) has two fundamental characteristics:
      • Endogenous rhythmicity with a period of approximately 24 hours that persists independently of oscillations in external factors such as the light/dark cycle
      • The ability to have its timing shifted by external factors such as light and nutrient intake
    • The importance of the circadian system is exemplified by the observation that circadian disruption leads to an array of disorders (eg; sleep disorders, impaired glucose regulation & obesity) and decreased life expectancy
    • Specifying of dynamic white LED lighting that can be adjusted for higher Correlated Color Temperature (CCT) in the morning and lower CCT in the evening time that can assist in reinforcing the circadian rhythm.


  1. Architectural Lighting
    • By understanding how lighting can compensate for common changes that happen to the aging eye, designers can improve the quality of life of older adults in assisted living facilities. Some of those factors where lighting can be used to improve the quality of life:
      • Development of light levels to meet the IESNA recommended levels
      • All lighting to be provided with minimal source brightness. Glare control accessories to be provided where required.
      • The use of dynamic white LED lighting can allow the lighting to respond to the changes in the inhabitant’s environment.
      • Lighting to be provided with sustainable light sources such as LED and CFL to maximize energy efficiency and provide cost savings.
      • The selection of material finishes can increase the ability of the lighting to blend in with its architectural environment.
  1. The Portals of Light

This is a proprietary AWA design solution developed especially for Assisted Living spaces, but this solution also remains pertinent for Special Needs patients (Alzheimer’s, Dementia, Autism etc.)

  • Provides quality lighting design solutions for both circadian and architectural lighting in transition locations (vestibules, foyers, lobbies, etc.). This helps in reducing the jarring impact that change in light levels brings to the residents in Assisted Living spaces. This system comes with a plug-n-play modularity that can be moved easily. It can be used to retrofit existing locations, or used for new construction.
  • By improving the lighting in these transitional spaces, we can provide improved healthcare for all inhabitants, especially those who are not as mobile.



  1. 2013 Fall; 7(1):60-78. Senior living environments: evidence-based lighting design strategies.
  2. RP-28-07. Lighting for the Visual Environment for Senior Living (ANSI Approved)
  3. Mariana G. Figueiro. 2001. Lighting the way: a key to independence. Lighting Research Center.
  4. M ariana G. Figueiro. 2013. A 24 Hour Lighting Scheme for Older Adults. Lighting Research Center.

Image Credit: Lighting Research Center (A 24 Hour Lighting Scheme for Older Adults)

Lighting Design Strategies To Improve Health

Michael David White, senior lighting designer, Schuler Shook, presented a compelling argument for a new approach to lighting design within senior living environments during his session at the 2013 Environments for Aging Conference. Backed by research that was thoughtfully and clearly explained, White laid out the evidence to support a broader definition of lighting itself, drawing a distinction between “visual darkness” and “circadian darkness.”

Circadian rhythms—the biological patterns that fall within a 24-hour cycle—can play an important role in health and wellness, White explained. While this concept isn’t news to anyone in the healthcare industry, White took the specific tack of linking circadian sleep patterns with health outcomes of seniors living in long-term care environments. “Many residents’ sleep patterns are disrupted in long-term care facilities,” he said, and pointed to how sleep disruption has been linked to issues such as depression, seasonal affective disorder, and even an increased risk of type 2 diabetes and cancer. “We’ve accepted [sleep disruption] as a normal function of aging—but it doesn’t have to be.”

The issue, he contended, is that light levels in these environments are typically kept low and many residents aren’t exposed to bright lights at any point during their regular day. “Evidence supports that it’s the disruption of circadian rhythms” that derails sleep patterns, he said, and “we can affect that through lighting.”

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Written by: Kristin Zeit

Source: Healthcare Design Magazine

Exposure to Light Could Help Alzheimer’s Patients Sleep Better

Individuals with Alzheimer’s disease and related dementias (ADRD) often sleep during the day and are awake at night. The situation can turn life-threatening if they leave their homes and wander around outside. This irregular sleep schedule and night wandering, and the consequent burden on their caretakers, is a primary reason individuals with ADRD are placed in more controlled environments such as nursing homes. A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute lays the foundation for the importance of tailored light exposures as a viable treatment option for the reduction of sleep disturbances in older adults and those with ADRD.

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Here is the LRC’s page about the study

Written by: Rebekah Mullaney

Source: Health Canal

The Potential of Outdoor Lighting for Stimulating the Human Circadian System

Every species on earth exhibits a wide range of biological cycles that repeat approximately every 24 hours. These are known as circadian rhythms (circa – approximately; dies – day) and are exhibited at every level of biological systems, from timing of DNA repair in individual cells to behavioral changes, like the sleep-wake cycle.

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Written by: Mark S. Rea, Aaron Smith, Andrew Bierman, Mariana G. Fiqueiro

Source: Lighting Research Center, Rensselaer Polytechnic Institute, Troy, New York