Effect of pulsing in low-level light therapy

Javad T. Hashmi, Ying Ying Huang, Sulbha K. Sharma, Divya Balachandran Kurup, Luis De Taboada, James D. Carroll, Michael R. Hamblin

Research output: Contribution to journalReview articlepeer-review

238 Citations (Scopus)


Background and Objective: Low level light (or laser) therapy (LLLT) is a rapidly growing modality used in physical therapy, chiropractic, sports medicine and increasingly in mainstream medicine. LLLT is used to increase wound healing and tissue regeneration, to relieve pain and inflammation, to prevent tissue death, to mitigate degeneration in many neurological indications. While some agreement has emerged on the best wavelengths of light and a range of acceptable dosages to be used (irradiance and fluence), there is no agreement on whether continuous wave or pulsed light is best and on what factors govern the pulse parameters to be chosen. Study Design/Materials and Methods: The published peer-reviewed literature was reviewed between 1970 and 2010. Results: The basic molecular and cellular mechanisms of LLLT are discussed. The type of pulsed light sources available and the parameters that govern their pulse structure are outlined. Studies that have compared continuous wave and pulsed light in both animals and patients are reviewed. Frequencies used in other pulsed modalities used in physical therapy and biomedicine are compared to those used in LLLT. Conclusion: There is some evidence that pulsed light does have effects that are different from those of continuous wave light. However further work is needed to define these effects for different disease conditions and pulse structures.

Original languageEnglish
Pages (from-to)450-466
Number of pages17
JournalLasers in Surgery and Medicine
Issue number6
Publication statusPublished - Aug 2010
Externally publishedYes


  • Clinical trials
  • Duty cycle
  • Frequency
  • Low level light therapy
  • Photobiomodulation
  • Pulse duration

ASJC Scopus subject areas

  • Surgery
  • Dermatology


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