Pulsed vs Continuous Red Light Therapy: Does Pulse Mode Matter?

Continuous light is the standard setting for red light therapy, and it is what nearly all the human trials used. Pulse mode switches the light on and off many times a second, at a rate measured in hertz (Hz). In laboratory studies pulsed light has sometimes done better than continuous light at the same average dose, and 10 Hz stands out in two carefully matched experiments. The research has not yet tied any particular frequency to any particular result in people, so pulse mode is best treated as an extra setting to explore once a continuous routine is in place. This article explains what pulsing does, what the studies on 10 Hz and 40 Hz found, how pulsing changes the dose, who should not use it, and how to set a panel that offers both.

What does pulse mode do on a red light therapy panel?

It turns the LEDs on and off at a set rate instead of leaving them on. Four terms describe any pulse setting.

These definitions come from the main scientific review of pulsing in light therapy, which asks researchers to report all of them alongside the wavelength. Lasers in Surgery and Medicine, 2010 The review sets out several ideas for why pulsing might matter. The off periods let tissue shed heat. Ion channels in cells open and close on a scale of a few milliseconds, close to the timing of the pulses. And repeated pulses may release nitric oxide from the cell's energy enzyme more often than steady light does. All three are proposals that researchers are still testing.

Is pulsed red light therapy better than continuous?

In animal and cell studies it sometimes is. In people the two have rarely been compared, and continuous light is the setting the human evidence rests on.

The 2010 review examined 33 studies of pulsed light. Nine compared pulsed with continuous light directly: six found pulsed more effective, one found them equal, and two found continuous better. Its authors found some evidence that pulsed light has effects of its own, with the clearest signals in wound healing and recovery after stroke in animals. They also described continuous light as the gold standard that has been used for every application.

Pulsed LED light on its own has performed well in at least one controlled human trial. Forty participants used a 630 nm LED pulsed at a 40% duty cycle on the lower abdomen for 20 minutes a day over seven days in a double-blind crossover study, and reported pain scores fell from 6.63 to 3.63 with the active device against 7.30 to 6.75 with a sham. Photonics, 2024 There was no continuous arm, so the trial shows that a pulsed LED can work, and leaves open whether pulsing added anything.

What is special about 10 Hz?

It is the frequency that came out ahead in the two best-matched laboratory comparisons. Both used 810 nm lasers on animals and kept the average dose identical across groups.

• Mice, 2011: after a brain injury, groups of ten mice received one 12-minute session of 810 nm light at 36 J/cm², either continuous, pulsed at 10 Hz or pulsed at 100 Hz. The pulsed groups ran at double the peak power with a 50% duty cycle, so every group received the same average. Four weeks later the 10 Hz group had the best neurological scores, 0.60 against 1.30 for both continuous and 100 Hz light and 2.50 untreated. PLoS ONE, 2011
• Rats, 2016: skin wounds were treated for ten minutes a day with 810 nm light at 22.6 J/cm², continuous or pulsed at 10 Hz or 100 Hz. By day eight the light-treated wounds had contracted 53 to 64%, with the 10 Hz group ahead of both continuous and 100 Hz light. PLoS ONE, 2016

These are animal experiments with lasers, on injuries that home devices are not for. They are the reason 10 Hz attracts attention, and the reason it is the natural place to start if you want to try pulse mode. A small case series in people also used 810 nm LEDs pulsed at 10 Hz in a headset. Photomedicine and Laser Surgery, 2017

What is 40 Hz light therapy, and is it the same thing?

It is a separate line of brain research, and it reaches the brain by a different route from a body panel. Most of it uses visible light flickering at 40 Hz that a person watches, and some uses near-infrared headsets on the scalp.

The idea began with a 2016 study in mice, which reported that 40 Hz flickering light lowered amyloid protein levels in the visual part of the brain. Nature, 2016 A pilot in people followed: 15 volunteers with mild Alzheimer's disease sat with a 40 Hz light and sound device or a steady-light control for an hour a day over three months, and the device was safe and well tolerated. PLoS ONE, 2022 With near-infrared, a sham-controlled crossover study of 20 healthy older adults found that one 20-minute session of 810 nm light pulsed at 40 Hz from a headset shifted resting brain-wave patterns. Scientific Reports, 2019

This is active research on the brain, done with purpose-built equipment. A body panel set to 40 Hz and pointed at a knee or a face is a different thing, and the brain studies say nothing about it either way.

Does pulsing change the dose?

Yes, whenever the brightness during each flash stays the same. Average power is peak power multiplied by the duty cycle, so at a 50% duty cycle the same session delivers half the energy.

The dose formula is the one we use in how much red light therapy is too much: joules per square centimetre equals average milliwatts per square centimetre, times seconds, divided by 1,000. In the 2024 trial above, a 25 mW/cm² peak at 40% duty gave 10 mW/cm² on average, or 12 J/cm² over 20 minutes. The frequency itself does not enter the sum: 10 Hz and 1,000 Hz at the same duty cycle deliver the same average.

Two practical points follow. If pulse mode keeps the same brightness and switches it on and off, a pulsed session delivers less light than a continuous one of the same length. And a pulsed session is not a reason to go beyond the times in the manual.

Which frequency should you set?

Continuous for your regular sessions, since that matches the human trials. If you want to try pulsing, 10 Hz is the setting that came out ahead in the two best-matched animal studies, and the frequency charts that assign a benefit to every number are ahead of the science.

Charts that list one frequency for sleep, another for collagen and another for pain are common, some of them based on a set of seven frequencies devised for ear acupuncture in the 1970s. Wikipedia The 2010 review looked for a pattern of this kind across the pulsed-light studies and reported: "It was impossible to draw any meaningful correlations between pulse frequency and pathological condition". Benefits appeared at frequencies from about 2 Hz to 8,000 Hz, with none consistently best.

Is pulse mode the same as a super-pulsed laser?

No. A super-pulsed laser fires bursts lasting billionths of a second at peaks of several watts, while an LED panel in pulse mode switches its LEDs on and off many times a second.

The classic super-pulsed device is the 904 nm gallium-arsenide laser used in physiotherapy, whose pulses last 100 to 200 billionths of a second according to the 2010 review. The World Association for Photobiomodulation Therapy publishes a separate dose table for it, specifying a peak pulse output above 1 watt. WALT Results from those lasers belong to those lasers. The differences between laser and LED light are covered in cold laser therapy vs red light therapy.

Is pulsed red light safe, and who should avoid it?

With goggles on, no extra risk has been reported for most people. Anyone with epilepsy should not use it, because flashing light at low frequencies can trigger seizures in people with photosensitive epilepsy.

The Epilepsy Society says around 3% of people with epilepsy are photosensitive and that "Between 3-30 hertz (flashes per second) are the common rates to trigger seizures". Epilepsy Society The Epilepsy Foundation gives the most likely range as 5 to 30 flashes a second. Epilepsy Foundation A panel's low pulse settings fall inside that band, which is one reason epilepsy is on our precautions list for both devices.

For everyone else the rules are the ones that apply to any session. Put the goggles on before the light comes on, keep your eyes closed when facing the panel, and remember that other people and pets in the room can see the flicker too. If a pulse setting feels unpleasant or brings on a headache, switch back to continuous. Eye safety is covered in is red light therapy safe for your eyes.

Do Kivorla devices pulse?

The panel does, anywhere from 1 to 10,000 Hz, and it also runs continuously. The mask is continuous only.

The 9-Spectrum Red Light Therapy Panel has nine wavelengths from 480 to 1060 nm, each dimmable from 1 to 100% on its own, a timer of 1 to 30 minutes and a controller for the settings. Suggested use is 10 to 15 minutes per area, at 6 inches for a joint or 12 inches for a broad area, with at least six hours between 30-minute sessions and the supplied goggles on. A sensible way to use the pulse range is to build a routine on continuous light first, then try 10 Hz for the same session and see whether you prefer it. Setting up is covered in how to set up a red light panel at home.

The 4-Wavelength Red Light Therapy Mask delivers continuous light at 50 to 103 mW/cm² with a 5, 10 or 15-minute timer. Standard shipping to the US, UK and Germany is free. Read the precautions before ordering, since returns are accepted within 30 days, less a 10% restocking fee if the device is unopened with its seals intact, or 20% if it is opened but undamaged and complete.

Kivorla devices are general wellness devices, not medical devices. The studies described here used research lasers and headsets, often in animals or in people with medical conditions, and are not claims about what our devices treat. Do not use either device if you have epilepsy.