•The circadian rhythm regulates crucial biological activities.
• Disrupting these activities can lead to health problems including weight gain, slower thinking, weakened immune system, heart disease and cancer.
•Light is the main cue for setting our circadian clock.
•While human eyes evolved to see blue wavelength light during the day, exposure to blue light at night (phones, TV, tablets and computer screens) will disrupt our circadian rhythm.
•Technological innovations like F.lux and Apple’s Night Shift are available to help us reclaim our circadian rhythms.
• Regulating a natural circadian rhythm will increase quality of sleep, decrease stress, diminish aggression, reduce blood pressure and facilitate an overall healthier functioning body and mind.
•LED color controllable lights are now available for work environments.
The 24-hour light-dark cycle is one of the most intrinsic features of Earth. This daily light rhythm was so important to our survival, in fact, that humans evolved a circadian clock just to monitor it.
“Circadian”, a term coined in 1959 from Latin circa (about) and diem (day), is used to describe rhythmic biological cycles recurring approximately every 24-hours. Some of the most notable biological activities that are regulated by our circadian rhythm include:
+ brain wave activity
+ cell regeneration
+ hormone production
+ body temperature
+ sleep
These tasks are critical for humans to optimize their health and happiness, and yet day after day most humans sabotage their intrinsic circadian cycles without even realizing it.
Since the rising and setting of the sun is the most influential daily occurrence for humans, we naturally evolved to be light sensitive. Aside from influencing the way we see the world, light directly affects our temporal rhythms of sleep and wakefulness.
Light is the main cue influencing our circadian rhythm, and our brains are programmed to perform differently under various light settings. To maintain optimal circadian health, it is imperative to time our exposure to certain light wavelengths in accordance with the natural light-dark cycle that our sun provides.
Humans evolved without artificial light for thousands of years. In the morning, the sunlight appears in mostly blue wavelengths (400-500nm). As the midday approaches, the wavelengths shift to green (500-600nm), and finally move to the red spectrum (600-700nm) in the evening.
The man-made lights we encounter in our everyday working lives are predominately blue in wavelength. Blue wavelength light triggers the production of serotonin and cortisol, which help the body achieve elevated mood and alertness. These feelings are welcome when you want to tackle the day, but problems arise when you work late nights under the same “morning blue” light setting.
The presence of blue wavelength light suppresses the production of melatonin, a hormone that acts to predict the daily onset of darkness. Only when blue light is absent will our bodies begin preparation for restorative sleep.
When we sense red light wavelengths above 600nm, our bodies activate anti-cancer and anti-viral cells. Red light and total darkness are critical indicators that allow our bodies to enter this restorative phase.
Exposure to blue light at night disrupts our natural circadian rhythm and can lead to:
+ poor sleep
+ high stress
+ increased anxiety
+ depression
+ cardiovascular disease
+ type II diabetes
+ higher incidence of breast cancer
So how are we sabotaging this natural cycle? Bright office lighting, cell phones, tablets, computers and TV screens all emit rich blue light.
How often do you find yourself awake at night on your phone or watching TV, wondering why you can’t fall asleep? You might not be a night owl. You might just be tricking your body into thinking it’s daytime. A typical cell phone screen can emit up to 200 lumens of rich blue light, which is enough to trigger a circadian response in most individuals when viewed at night.
The bigger the screen, the more blue light is being absorbed by your Retinal Ganglion cells and suppressing melatonin production – disrupting your circadian clock. Larger screens such as tablets, computers and most significantly, T.Vs, are the worst culprits. Fluorescent light bulbs produce light wavelengths at 400 to 450nm, the exact wavelengths that signal to your brain it is day.
Ditching technology and running into the woods as soon as the sun sets, thankfully, is not the only option. Research on the importance of circadian rhythms has led many tech providers to make changes to the way our devices emit light at night.
F.lux is free computer lighting software that synchs the color temperature of your display with your geographic sunrise and sunset. Instead of constantly emitting blue-white “morning” light, the F.lux controlled screen emits a soothing warm red in the early morning and evening. This color adjustment mimics the light-dark cycle our physiology evolved to recognize. Programmed and co-invented by Michael Herf, F.lux is available for Mac, Windows, and Linux.
The latest Apple software update includes a “Night Shift” feature (Settings > Display & Brightness), which allows users to adjust the color temperature of their phones according to sunrise, sunset, or customized times. The Night Shift feature adjusts color for the entire mobile display (not just a single app), and represents an enormous step forward in protecting our circadian rhythm.
The Lighting Research Center has also come out with a sensor that measures circadian light reaching the eye. Coupled with smart devices, this sensor will help people manage their personal light-dark cycles. A better understanding of our personal circadian rhythm will allow users to increase restorative sleep, enhance performance and improve health.
Color adjustable LED lights paired with smart controls are bringing “human centric lighting” to homes and the office. The IoT (Internet of Things) is generating integrated light systems that sense human presence and emit colors to fit the circumstance.
The circadian clock consists of a group of nerve cells called the suprachiasmatic nucleus (SCN). This “master clock” is located in the hypothalamus of the brain, just above where the optic nerves from the eyes cross.
The SCN sends signals to the brain to regulate everyday biological functions like sleep and cellular regeneration. Similar to winding a pocket watch, the SCN maintains its accuracy by resetting itself daily using external cues.
Most people are familiar with rods and cones, the photoreceptors in our eyes that allow us to see shapes and color. But few know of the special cells in the retina called intrinsically photosensitive Retinal Ganglion Cells (ipRGCs), which contain the light-sensitive pigment melanopsin.
Melanopsin is most sensitive to short wavelength blue light. In fact, peak sensitivity for ipRGCs comes in the wavelength of about 420 to 480 nanometers (sky blue). High intensity of this blue light on the optic nerve signals to the SCN that its time to wake up. Conversely, low intensity of blue light means it’s time to sleep.
The results of properly maintaining our circadian clock are nothing short of remarkable. Various studies throughout the last 30 years have shown that light treatments done to correct circadian rhythm have greatly reduced or even eliminated the symptoms of people affected by jet lag, Seasonal Affective Disorder and shift work. Correcting patients’ circadian rhythm acted as an anti-depressant, increased alertness, heightened immune response and reduced stress and fatigue.
The circadian rhythm regulates crucial biological activities.
Disrupting these activities can lead to health problems including weight gain, slower thinking, weakened immune system, heart disease and cancer.
Light is the main cue for setting our circadian clock.
While human eyes evolved to see blue wavelength light during the day, exposure to blue light at night (phones, TV, tablets and computer screens) will disrupt our circadian rhythm.
Technological innovations like F.lux and Apple’s Night Shift are available to help us reclaim our circadian rhythms.
Regulating a natural circadian rhythm will increase quality of sleep, decrease stress, diminish aggression, reduce blood pressure and facilitate an overall healthier functioning body and mind.
LED color controllable lights are now available for work environments.
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