pulsed red light therapy devices

Why would you want to pulse red light therapy, and how do you get it? This blog will explore the important aspects you need to know before purchasing a red light panel or photobiomodulation product that features pulsing.

What is pulsing?

Pulsing is typically a rapid "on" and "off" of a device. In contrast, most studies use continuous light therapy, simply meaning the light is "on" for the entire time of the treatment.

Oscilloscope Continous Wave
Oscilloscope image of "continuous" wave - the light is simply "on" the entire time.


The pulse frequency refers to the the interval between the "on" time to the next "on" time. This is measured and communicated in units of Hertz, or Hz.

Hertz is simply the cycles per second. 

Red Light Therapy Pulse Oscilloscope 10hz
Oscilloscope image showing the square-like form of pulsing with "on" and "off" sections.


So if we say 10 Hz, then the light is flashing on and off 10 times per second.

With pulsed red light therapy there is typically a "duty cycle" of 50%. Which means there is an equivalent amount of time in the "on" position and "off" position.

This also informs us that compared to continuous wave, a pulsed light will have an average intensity of half of the continuous.

Why do pulsing?

There are 3 main reasons people might be interested in adding pulsing to their photobiomodulation technique.

In order of clinical relevance:

1. Reduce tissue heating.

2. Brainwave entrainment.

3. Some special mechanism or benefit.

Number 1 is probably the most studied in clinical studies. Number 2 has the most practical consumer applications especially for brain health. And Number 3 doesn't have much data, but is heavily abused by brands and marketing.

Let's look at them a bit deeper:

1. Reduce tissue heating.

The first benefit of pulsing is probably the most well-studied in clinical literature.

In the origins of red light therapy they were using lasers, but they needed to be low enough power to be safe and not cause tissue heating or burns.

One of the most effective techniques to reduce tissue heating and still get great benefits is by pulsing. The short "off" times can help the tissue cool to thermoregulate and prevent overheating.

Now this technique enables increasing the laser or LED intensity without causing thermal damage.

So the clinical studies will often compare a pulsed light at a higher peak intensity versus a continuous wave light at half the power of the pulsed light.[1]

Is the benefit really the extra peak intensity, or something more with a special mechanism around pulsing? That's what we need to make clear.

2. Brainwave entrainment.

The second benefit of pulsing is to induce brainwave entrainment. We know that our neurons can synchronize with the frequencies lights and sounds around us.

Using frequencies like 10 Hz (for alpha brainwaves) and 40 Hz (for gamma brainwaves) may help the brain synchronize with beneficial brain states.[3]

These brainwave entrainments has implications help with disease states like Parkinson's and Alzheimer's and restoring the brainwaves to a natural order.

This is the easiest to implement with flashing lights to the eyes, or transcranial and intranasal application of red light therapy. For example Vielight has successfully marketed "Alpha" and "Gamma" intranasal and transcranial lights for years.

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