In the late 1960's, researchers introduced the concept of laser biostimulation using low-powered laser beams to produce non-thermal effects in human tissue. The first experimental applications of low-level laser therapy (LLLT) were reported in 1968, when researchers used ruby and argon lasers on non-healing or slow-to-heal ulcers. Later research substantiated the efficacy of laser treatment to accelerate the healing of wounds, attenuate pain, and reduce tissue inflammation in both humans and animals.

To treat chronic pain with laser biostimulation, one must reach deep into tissue to irradiate the affected area. Laser wavelengths between 820 nanometers to 840 nanometers have an extremely low absorption rate in human tissue, thus allowing deep penetration of laser light. The 830 nm laser beam is also well absorbed in subcellular organelles, causing them to function normally. The laser's low level of power output also affects the depth of the beam's penetration, and has been shown to be effective in treating human tissue. The 830 nm laser with a power output between 60 milliwatts (mW) and 90 mW is reported by experimenting clinicians to be optimal for treating chronic pain.

Damaged cells, on examination, show that a dysfunctional nerve network, lymphatic system, or circulatory system, or possibly all three, produce an imbalance or abnormal condition. LLLT is effective in large part because it focuses on the interdependent relationship between the nerve network, lymphatic and circulatory systems. Although it is possible for damaged cells to normalize without LLLT, the use of LLLT may speed up the normalization process.

A good example of how LLLT speeds up the normalization process can be demonstrated with acute soft tissue trauma. An injury of this type consists of damage to several elements involving the deep, sensitive layers beneath the epidermis; including muscular, neural, lymphatic and vascular tissue. The human body's natural reaction to acute soft tissue trauma is to "splint" the injury with edema, an accumulation of thin or watery fluid in tissue spaces or cell interstices, causing a swelling. This swelling prevents excessive movement of the damaged tissue and results in two types of pain. The first type is actual trauma pain from the injured tissue, while secondary pain comes from the swelling itself.

Low-level laser therapy first targets the lymphatic system, because it maintains the fluid balance in the body; and the infrared laser light also improves reabsorption of the edema. With LLLT, swelling is reduced, allowing movement to return to the treated area.