Circadian Rhythms and Tunable White: What You Need to Know

Posted on by admin

Close up image of human hand holding electrical bulb


What’s all the fuss about “tunable white?”

The lighting industry is abuzz with tunable white technology, and it’s turning up in everything from recessed lights to table lamps

Not only is it a cool new technology, research shows that tunable white fixtures might actually be beneficial for health and well-being if they’re used the right way in the right applications.



Let’s take a look at some recent research about the connection between lighting and circadian rhythms.

Mariana Figueiro is Director of the Lighting Research Center at Rensselaer Polytechnic Institute. Throughout her career, she has explored how light affects human health.[1]

She recently authored a study focused on nursing home residents with Alzheimer’s disease. In this study, she found that certain kinds of lighting improve sleep patterns, reduce agitation, and alleviate depression.

Here’s a brief (and rudimentary) recap of the study’s methodology:

  • Figueiro and her team used custom-designed LED table lights or individual room lighting.
  • They implemented these lights for 43 nursing home residents over a course of four weeks and 37 nursing home residents over a course of six months.
  • After four weeks, there were significant declines in sleep disturbance and depression scores for patients involved in the study. After six months, the patients’ sleep disturbance scores had lowered by about half. Depression scores, on average, were less than half of the baseline levels.[2]

Learn more about the study here. (Note: The research was presented at the Alzheimer’s Association annual meeting in July. The study itself hasn’t been published yet.)


So, what was so special about the lighting used in the study?

The researchers used lighting designed to mimic patterns of natural daylight and stimulate the human circadian rhythm. Think of the circadian rhythm as the body’s internal clock that tells us what time of day it is and whether we should be alert or asleep. Light is one of the main cues that stimulates the circadian rhythm and keeps it “on-time.”

To keep the circadian rhythm synchronized, ideally we want the lighting around us to mimic natural daylight, including the shifts in color and brightness that natural daylight undergoes throughout the day.

Spending most of the day in an environment where light levels are unnatural can confuse the circadian rhythm, disturbing the cycle and leading to health problems. These health problems can include issues with sleep and mood, something that can happen to nursing home residents in particular due to the amount of time they spend indoors under artificial lights.

By introducing into patients’ rooms lighting designed to mimic natural daylight patterns, Dr. Figueiro and her team created an environment that stimulated the innate, normal cycle of each patient’s circadian rhythm.


The shifts in color and brightness daylight goes through during the day affects the circadian rhythm.


How can we mimic natural daylight patterns in our own homes?

Here’s where tunable white technology comes in. Tunable white LED fixtures make it possible to imitate the color and brightness shifts of natural daylight like never before.

Daylight undergoes many changes throughout the day, but here’s a rough overview:

  • Lighting in the morning and early afternoon should be bright and include blue wavelengths of light (in other words, you want your light source to be a higher color temperature).
  • By the late afternoon and evening, lighting should be less bright and more amber in color (so you’ll want the light source to be a lower color temperature).

Tunable white LED fixtures allow you to adjust the color temperature of your lighting, tuning it to a bluer, whiter light or a warmer, more amber light depending on the time of day. (Read all about tunable white light here.)

Advanced but easy-to-use lighting control systems also allow you to dim and adjust the brightness of your light fixtures to create different scenes for different times of day.


Interested in how you can bring this kind of lighting into your home or office building?

Click below to set up an appointment. We’d love to discuss the possibilities with you! Not only can we guide you on lighting products, we can also design and install the solutions, thanks to our technology division: System 7.



0 Comments | Blog

Comments are closed.

  • Archives