How long you need to use the panel depends on your goals, but one collection of studies looking at red light therapy for anti-ageing and skin rejuvenation found a clear “sweet spot” in the dose range. This is often called the biphasic dose response, where light is beneficial up to a point, but beyond that, the effects plateau or even start to decline.

According to these findings, the most effective range for skin-related benefits sits between 5 and 9 J/cm². Anything below around 1 J/cm² or above 30 J/cm² is unlikely to have a significant effect. For example, when using the CELLER8 full-body panel at a distance of 12 inches, your skin receives around 50 mW/cm² of light intensity. That means a session of roughly 1 minute 35 seconds gives about 5 J/cm², and 3 minutes gives around 9 J/cm² the optimal window for stimulating collagen and rejuvenating skin.

In short, for most skin and anti-ageing goals, short, consistent sessions in the 5–9 J/cm² range appear to provide the best balance of energy and effectiveness.