Low-level laser (light) therapy (LLLT), also known as photobiomodulation, has been used for decades to treat various medical conditions. It involves exposing cells or tissues to low-intensity red and near-infrared (NIR) light, which is referred to as "low level" due to its use of light at energy densities lower than other forms of laser therapy. LLLT is also known as "cold laser" therapy because the power densities used are lower than those needed to produce heating of tissue. Initially, it was believed that LLLT required coherent laser light, but recent studies have shown that light-emitting diodes (LEDs) can also be effective. LLLT has been shown to have a wide range of effects at the molecular, cellular, and tissue levels. It is believed to act on mitochondria to increase adenosine triphosphate (ATP) production, modulate reactive oxygen species (ROS), and induce transcription factors. These factors then cause protein synthesis that triggers further effects such as increased cell proliferation and migration, modulation of cytokine levels, and increased tissue oxygenation. LLLT has been shown to promote wound healing by inducing the release of cytokines, chemokines, and other biological response modifiers that reduce the time required for wound closure and increase the mean breaking strength of the wound. LLLT is also used to relieve inflammation and edema due to injuries or chronic diseases, and as an analgesic and treatment for neurological problems. It has been shown to be effective in treating chronic joint disorders, such as osteoarthritis, and in alleviating pain from cervical dentinal hypersensitivity and periodontal pain during orthodontic tooth movement. LLLT has also been considered as a viable treatment for serious neurological conditions such as traumatic brain injury (TBI), stroke, spinal cord injury, and degenerative central nervous system disease. Intravascular laser therapy involves the in vivo illumination of blood by feeding low-level laser light through a fiber optic inserted in a vascular channel. It is claimed to improve blood flow and its transport activities, but has not been subject to randomized controlled trials and is subject to skepticism. Laser acupuncture may be used solely or in combination with needles for any given condition over a course of treatment. LLLT has also been used for hair regrowth in balding individuals, with the Hairmax Lasercomb shown to give a statistically significant improvement in hair growth in a randomized, double-blind, sham device-controlled, multicenter trial. The mechanisms of LLLT are not yet fully understood, but it is believed to involve the activation of mitochondrial activity and the modulation of transcription factors. The dose response of LLLT is biphasic, with lower doses of light often more beneficial than high doses. The choice of parameters such as wavelength, fluence, power density, pulse structure, and timing of the applied light is crucial for the effectiveness of the treatmentLow-level laser (light) therapy (LLLT), also known as photobiomodulation, has been used for decades to treat various medical conditions. It involves exposing cells or tissues to low-intensity red and near-infrared (NIR) light, which is referred to as "low level" due to its use of light at energy densities lower than other forms of laser therapy. LLLT is also known as "cold laser" therapy because the power densities used are lower than those needed to produce heating of tissue. Initially, it was believed that LLLT required coherent laser light, but recent studies have shown that light-emitting diodes (LEDs) can also be effective. LLLT has been shown to have a wide range of effects at the molecular, cellular, and tissue levels. It is believed to act on mitochondria to increase adenosine triphosphate (ATP) production, modulate reactive oxygen species (ROS), and induce transcription factors. These factors then cause protein synthesis that triggers further effects such as increased cell proliferation and migration, modulation of cytokine levels, and increased tissue oxygenation. LLLT has been shown to promote wound healing by inducing the release of cytokines, chemokines, and other biological response modifiers that reduce the time required for wound closure and increase the mean breaking strength of the wound. LLLT is also used to relieve inflammation and edema due to injuries or chronic diseases, and as an analgesic and treatment for neurological problems. It has been shown to be effective in treating chronic joint disorders, such as osteoarthritis, and in alleviating pain from cervical dentinal hypersensitivity and periodontal pain during orthodontic tooth movement. LLLT has also been considered as a viable treatment for serious neurological conditions such as traumatic brain injury (TBI), stroke, spinal cord injury, and degenerative central nervous system disease. Intravascular laser therapy involves the in vivo illumination of blood by feeding low-level laser light through a fiber optic inserted in a vascular channel. It is claimed to improve blood flow and its transport activities, but has not been subject to randomized controlled trials and is subject to skepticism. Laser acupuncture may be used solely or in combination with needles for any given condition over a course of treatment. LLLT has also been used for hair regrowth in balding individuals, with the Hairmax Lasercomb shown to give a statistically significant improvement in hair growth in a randomized, double-blind, sham device-controlled, multicenter trial. The mechanisms of LLLT are not yet fully understood, but it is believed to involve the activation of mitochondrial activity and the modulation of transcription factors. The dose response of LLLT is biphasic, with lower doses of light often more beneficial than high doses. The choice of parameters such as wavelength, fluence, power density, pulse structure, and timing of the applied light is crucial for the effectiveness of the treatment