LED Light Flicker and Your Red Light Therapy DeviceLast Updated:
Any fluctuation in the brightness of a light is considered a flicker. Flickering may be very visible, barely perceptible, or invisible to the human eye. Note - it is not the same as pulsing, which is a purposeful intermittent delay usually used in laser therapy to avoid skin burn.
Human reaction to flickering is highly subjective. Some people are very tolerant of high flicker levels, while others experience physical disturbance in response to even an almost imperceptible flicker.
Regardless of your tolerance level, flicker does not affect the healing and rejuvenating properties of red light therapy. Flicker poses no danger and it does not disrupt or diminish the effectiveness of red light therapy.
In this article, we will discuss the fundamentals of LED light flicker and what to look for when purchasing a red light therapy device for home use.
Table of Contents
Light Flicker Basics
First, we need to understand what causes LED light flicker, how it is measured, and how it can potentially impact our bodies.
AC Versus DC Power
Electrical currents can be one of two types:
- Alternating Current (AC) — AC power flows cyclically forward and in reverse. Its waves flow back and forth as the current alternates between positive and negative charges. This process represents the electrical cycle and is measured in Hertz (Hz), or cycles per second. AC power has a frequency of either 50 or 60 Hz, depending upon your location. AC power can transmit electricity over long distances and is the current by which our homes are powered.
- Direct Current (DC) — DC electrical charge flows in only one direction. Unlike the oscillating AC waves, DC power flows in a straight line. DC power has no frequency because it does not alternate. It can travel only short distances and is used for low voltage applications like battery-operated devices.
Since AC power travels over some distance to reach your home, any power surge, wiring glitch, or power line disturbance (wind or tree branches, for example) can disrupt the AC electrical frequency. This is the cause of flicker.
LED bulbs are inherently DC in nature; however, your device must be plugged into an electrical wall outlet to turn on and operate. Because they are ultimately running on AC power, red LED light panels take on the characteristics of AC electricity.
Any LED light that is powered by AC (including red light therapy panels) will flicker to some degree; this is innate to the functionality of AC power.
Two parameters are used to measure light flicker: frequency and percentage.
- Frequency — Flicker frequency is measured in Hertz (Hz), defined as one cycle per second. Frequency measures the recurrence of flicker; so, if light flickers 10 times per second, it would be measured as 10 Hz.
- Percentage — Flicker percentage equals the difference between the maximum and minimum brightness. If the light flickers completely off, the percentage of flicker is 100 percent. If it only dims slightly, say five percent below its maximum brightness, the flicker percentage is only five and the flicker is much less obvious.
How We Perceive Light Flicker
The relationship between flicker percentage and frequency determines how noticeable flicker is to the human eye and how likely it is to cause physical disturbances.
When the percentage is very low, flicker is barely perceptible (even invisible) no matter what the frequency. It is very unlikely to create physical effects.
As the flicker percentage rises, the lower the frequency, the more noticeable the flicker and the higher the possibility of adverse reactions.
The correlation between flicker percentage and frequency is key to the perception of light flickering and its potential to cause visual disturbances or adverse physical reactions.
Potential Physical Effects of Light Flickering
Light flicker is an unnatural stimulus for your brain. Natural light sources do not flicker on and off multiple times per second; however, man-made light sources can. The same problem occurs when you sit under fluorescent lighting.
Flicker affects people differently. Some people might be sensitive to even a minor flicker, and others might not be bothered by obvious flickering.
If you are flicker-sensitive, you might experience:
- trouble concentrating
- muscle tension
- chronic low-level stress
Even for those who are sensitive to flicker, the potential side effects are not dangerous; they are simply uncomfortable or annoying.
As further evidence that flicker does not pose a safety issue, one study shows that flickering light might be beneficial in treating Alzheimer’s disease. Further, the recent trend of pulsed laser light laser therapy demonstrates that fluctuation in light therapy can sometimes be beneficial and is not harmful.
What To Look For When Purchasing an At-Home Red Light Therapy Device
Depending on your sensitivity, flicker may or may not be of concern to you when choosing a device. You might be more focused on EMF levels or other considerations such as power density of the red light therapy device.
If flicker factors into your decision, choose a device with a flicker percentage as close to zero as possible.
Once you choose a device, you can begin to safely reap the healing benefits of red light therapy in the comfort of your own home.
The following links provide additional research and information on light flickering.
- sciencedaily.com – Flickering Light & Alzheimer’s (opens in a new tab)
- plos.org – Effects of Flickering Artificial Light (opens in a new tab)
- nature.com – Humans Perceive Flicker at 500 Hz (opens in a new tab)
- ijpp.com – Flickering Light in Rats (opens in a new tab)
- bio-licht.org – Practices for Mitigating Health Risks (opens in a new tab)
Flickering is not a safety concern when using red light therapy. Light flicker does not disrupt the delivery of red light to your skin, and the quality of therapeutic results is not affected by flicker.
Red light therapy is 100 percent natural, FDA-approved, and safe for all ages and skin types. Your entire body can benefit at its cellular level from this revolutionary, life-changing treatment.