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For some, the results of red light therapy at home are apparent within a few weeks. For others, it takes several months before they see the slightest results. While this can be discouraging, it’s important to remember that red light therapy is not a one-size-fits-all solution. Results often vary per user, and are affected by various factors - including the type of red light therapy device used, the person’s biology, consistency, and duration among others. In this spread, one of the most crucial involves the dosage employed.
Like most drugs or treatments, going beyond the “sweet spot” in dosage may produce negative results, while too little can deem the therapy ineffective. However, it’s important to note that the “correct dosage” is not one singular number, and varies depending on the user's goal. This article will explore the intricacies of finding the correct dosage for red light therapy and how to compute it on your own.
Red light therapy (RLT) is generally considered safe and non-invasive. There have also been no reported side effects, however, the key here is proper dosing. Dosage pertains to the quantity of light therapy you’re exposing yourself to, and each specific treatment goal requires a different number for success. A few factors including the area being treated, the device being used, and the individual’s overall health condition can affect the “correct” dosage.
While it’s easy to assume that a higher light dosage will be more beneficial and help achieve faster results, this is not entirely true. Red light therapy is biphasic, meaning lower light levels have more beneficial effects than higher levels. This can be demonstrated by a recent study exploring the effects of RLT on diabetes, which involved using an LED flexible pad with 830 nm LEDs on 10 patients with type 2 diabetes. The patients received either a 5.71 J/cm^2 or 13.72 J/cm^2. The outcomes revealed that the lower dosage stimulated better blood sugar control effects. The higher dosage was not as effective.
On the other hand, some studies discovered positive outcomes in much higher dosages, such as 20J/cm² and 70J/cm². A recent review conducted on studies discussing the effects of photobiomodulation on improving athletic performance and recovery found the best results at 30J/cm². Another review, however, found studies that used higher than 80J/cm² led to a negative response.
Various studies specify different sweet spot numbers, but it generally falls between 2–100 joules per square centimetre (J/cm²) for optimal effects on the cells. This number, however, is only a vague guide. The optimal dosage for each person has to be tailored to their current health condition and needs.
Understanding how to compute light therapy dosage is especially helpful for those using red light therapy at home. It ensures that users receive an appropriate dosage to achieve desired results. To compute the light therapy dose, these are the givens you’ll need:
You can use an optical power sensor to find the power density of any red light device. These devices are sensitive to light in the 400 nm - 1100 nm range, and explains why they’re not functional for incandescent and heat lamps, as the output of these devices is not within the relevant range for light therapy.
Some manufacturers also provide their device’s power density on their website or packaging, but, it’s best to take these with a grain of salt. Some may provide inflated or incomplete information to help their devices appear better.
The standard formula for light therapy dose is:
Power Density x Time x 0.001 = Dose
For example, if you use a device that emits 25 mW/cm2 in 40 seconds, the dose you have received is:
(25 x 40) x 0.0001 = 1J/cm²
If you have identified the dose you need for a specific goal and the power density of your device, you can determine how long each red light therapy session should last through this equation:
Dose (J/cm²) ÷ (Power density (mW/cm²) x 0.001) = Time (seconds) =
For instance, you’ll need a 10 J/cm2 dose and the power density of your device is 25 mW/cm2. You’ll get the following:
10 / (25×0.001) = Time
= 400 seconds
Converted into minutes, you’ll need approximately 6.67 minutes of red light therapy to get a 10 J/cm2 dose.
Using the right dosage is key to maximising the effects of red light therapy. However, it’s important to remember that the treatment affects each person differently. Even with the right dosage, different individuals will see effects in different time frames and at different levels. Consulting with a healthcare professional is advisable to ensure that every aspect of your RLT treatment is fit for your specific needs.
Learn more about other aspects of red light therapy, such as the importance of irradiance and how different red light therapy devices compare, at our ROJO blog. If you want to know more about our products for red light therapy at home, don’t hesitate to reach out to us!
