How long does a photobiomodulation session last?

The ideal duration of a photobiomodulation session depends on three main factors: the treatment area, the device’s power (irradiance), and the treatment goal (aesthetic, recovery, or pain relief).

The key is not to stay in the light for too long, but to reach the optimal dose absorbed by the cells, which is generally between 6 and 10 J/cm².

Average duration by area

• Face: 8 to 12 minutes
• Back, legs, hips: 15 to 20 minutes
• Specific joints (wrist, shoulder, knee): 5 to 10 minutes
• Brain (transcranial): 10 to 20 minutes, depending on the power
• Skin (wrinkles, acne, scars): 10 to 15 minutes, depending on the severity

Effect of irradiance on duration

• A high-power device (e.g., 100 mW/cm²) allows for a shorter session (~6 minutes)
• Conversely, a device with low power (e.g., 20 mW/cm²) will take longer (~20 minutes)
• The goal is to reach the target dose (e.g., 10 J/cm²), not to exceed an arbitrary threshold

💡 Example: with an irradiance of 30 mW/cm² → 10-minute session ≈ 18 J/cm² (too much = loss of effectiveness)

A biphasic curve: less may be more

Studies show that too much light can counteract the desired effects. This is known as the biphasic curve: beyond a certain dose, the benefits diminish. It is therefore best to:

• To adhere to the time limits for each zone
• Avoid scheduling too many long sessions
• Spacing out workouts if results plateau

At the office or at home: does it take the same amount of time?

• Professional devices are often more powerful: sessions are shorter (8 to 15 minutes)
• At home, for handheld devices or soft LED lights, the treatment time is between 12 and 20 minutes
• In any case: it’s better to be consistent than to have infrequent long exposures

For healthcare professionals

• Treatment time in the office: 8 to 15 minutes, depending on the area
• Some devices allow for automated configuration (time, spectrum, cycle)
• Monitoring of individual response is recommended (pain, inflammation, fatigue, etc.)

Scientific sources cited

• Huang Y.Y. et al. (2009). Biphasic dose response in low-level light therapy.
  Link to the study
  → Explains that too much light inhibits the effects, justifying an optimal duration that should not be exceeded.
• Avci P. et al. (2013). LLLT in skin: stimulating, healing, restoring.
  Link to the study
  → Shows visible effects on the skin after as little as 10 minutes of exposure, depending on the power level.
• Karu T.I. (2010). Multiple roles of cytochrome c oxidase in PBM.
  Link to the study
  → Explains the metabolic phases of light absorption and why the effects are dose-dependent.
• Amaroli A. et al. (2018). PBM therapy: clinical protocols and timing.
  Link to the study
  → Overview of treatment durations by body area and tissue type, for both medical and aesthetic use.

See also

• How many photobiomodulation sessions per week?
• How many photobiomodulation sessions per week?
• Photobiomodulation: When Do You Start to See Results?