What does laser even do?
There is the type of high-powered laser that is used to ignite nuclear reactions or take out missiles mid-air, and then there is the type that we’re talking about: low-level laser therapy (LLLT), also known as photobiomodulation (PBM). This uses wavelengths of red and near-infrared light applied to the body. So, wait - it’s just light? What could that possibly do?
At this point, we know of several mechanisms that could be driving the treatment effects we see in patients [1-3]. [BRACE FOR SCIENCE JARGON] The main targets seem to be mitochondria (our little cellular power stations), and calcium ion channels (important cellular communicators). This seems to produce an increase in cell energy (ATP), modulation of calcium and other modulators inflammation, and increased protein synthesis. This all leads to increased cell metabolism, survival, and growth that has been seen in skin, muscle, nerves, lungs, hair... But is that useful? It can be.
What can it help?
Laser has shown the following benefits:
· LLLT has little to no adverse effects [3-7] which is especially clinically useful in vulnerable populations like the ill and the elderly
· Significant and nearly immediate pain relief for sports injuries 
· Reductions in pain/diability and improved quality of life (QoL) in chronic neck pain (cNP) in both the short and medium term [5, 6] and in chronic low back pain (cLBP) in the short term 
· Pain reductions in shoulder tendon pathology when used alone or in combination with exercise 
· Pain relief in jaw pain (TMJ disorder) was seen , but the effects were probably limited if the causes weren’t also treated e.g. stress, anxiety
· Increases in wound healing, but in conditions like ulcers the effects need to be combined with treatment of the cause (e.g. diabetes) to be effective 
· Increased bone healing and pain relief after surgery  but no evidence to show benefit in knee osteoarthritis 
· May be beneficial for nerve rehabilitation/regeneration [3, 13] and show good short-term pain relief in carpal tunnel syndrome  and neuropathic pain  but other applications require a lot more study
· There is even early evidence that LLLT can have beneficial effects on brain conditions such as depression, anxiety, or traumatic brain injury, but this still requires rigorous study [3, 16, 17]
- Pain relief e.g. neck pain, back pain, sports injuries
- Increased tissue regeneration e.g. sport injuries, wound or bone healing
- When minimised adverse effects are needed in treatment e.g. elderly, other illnesses
1. Hamblin, M.R., Mechanisms and applications of the anti-inflammatory effects of photobiomodulation. AIMS biophysics, 2017. 4(3): p. 337-361.
2. de Freitas, L.F. and M.R. Hamblin, Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy. IEEE journal of selected topics in quantum electronics : a publication of the IEEE Lasers and Electro-optics Society, 2016. 22(3): p. 7000417.
3. Hashmi, J.T., et al., Role of Low-Level Laser Therapy in Neurorehabilitation. PM&R, 2010. 2(12, Supplement): p. S292-S305.
4. Huang, Z., et al., The effectiveness of low-level laser therapy for nonspecific chronic low back pain: a systematic review and meta-analysis. Arthritis Research & Therapy, 2015. 17: p. 360.
5. Chow, R.T., et al., Efficacy of low-level laser therapy in the management of neck pain: a systematic review and meta-analysis of randomised placebo or active-treatment controlled trials. The Lancet, 2009. 374(9705): p. 1897-1908.
6. Gross, A.R., et al., Low Level Laser Therapy (LLLT) for Neck Pain: A Systematic Review and Meta-Regression. The Open Orthopaedics Journal, 2013. 7: p. 396-419.
7. Loreti, E.H., et al., Use of Laser Therapy in the Healing Process: A Literature Review. Photomedicine and Laser Surgery, 2015. 33(2): p. 104-116.
8. Takenori, A., et al., Immediate pain relief effect of low level laser therapy for sports injuries: Randomized, double-blind placebo clinical trial. Journal of Science and Medicine in Sport, 2016. 19(12): p. 980-983.
9. Haslerud, S., et al., The Efficacy of Low-Level Laser Therapy for Shoulder Tendinopathy: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Physiotherapy Research International, 2015. 20(2): p. 108-125.
10. Shukla, D. and M.R. Muthusekhar, Efficacy of low-level laser therapy in temporomandibular disorders: A systematic review. National Journal of Maxillofacial Surgery, 2016. 7(1): p. 62-66.
11. Santinoni, C.d.S., et al., Influence of low-level laser therapy on the healing of human bone maxillofacial defects: A systematic review. Journal of Photochemistry and Photobiology B: Biology, 2017. 169(Supplement C): p. 83-89.
12. Huang, Z., et al., Effectiveness of low-level laser therapy in patients with knee osteoarthritis: a systematic review and meta-analysis. Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society, 2015. 23(9): p. 1437-1444.
13. Mojarad, N., et al., The role of low level laser therapy on neuropathic pain relief and interleukin-6 expression following spinal cord injury: An experimental study. Journal of Chemical Neuroanatomy, 2017.
14. Franke, T.P., et al., Do Patients With Carpal Tunnel Syndrome Benefit From Low-Level Laser Therapy? A Systematic Review of Randomized Controlled Trials. Archives of Physical Medicine and Rehabilitation, 2017.
15. de Andrade, A.L.M., P.S. Bossini, and N.A. Parizotto, Use of low level laser therapy to control neuropathic pain: A systematic review. Journal of Photochemistry and Photobiology B: Biology, 2016. 164(Supplement C): p. 36-42.
16. Cassano, P., et al., Review of transcranial photobiomodulation for major depressive disorder: targeting brain metabolism, inflammation, oxidative stress, and neurogenesis. Neurophotonics, 2016. 3(3): p. 031404.
17. Rojas, J.C. and F. Gonzalez-Lima, Neurological and psychological applications of transcranial lasers and LEDs. Biochemical Pharmacology, 2013. 86(4): p. 447-457.