Weak red and near-infrared light delivered to the body to help cells make energy more efficiently. Best supported for easing joint and tendon pain, slowing worsening nearsightedness in children, and speeding wound healing and hair regrowth. Brain, metabolic, and aging uses remain early and mixed. Very safe; getting the dose right matters most. (Full Review)

Protocol

Wavelength

630–670 nm red, 810–850 nm near-infrared

Match wavelength to the target tissue; wrong wavelength can yield a null result.

Dose (fluence)

~4–10 J/cm² deep tissue; up to tens of J/cm² at skin surface

Biphasic response: too little does nothing, over-dosing a session can negate benefit.

Frequency

Repeated sessions, several times weekly over weeks to months

Delivered as discrete split sessions, not one large exposure; benefit depends on repetition.

Time to effect

Pain relief

Days to a few weeks

Over a treatment course for musculoskeletal pain.

Myopia slowing

Measurable over 3–12 months

Slow response requiring consistent use.

Wound healing

Days to weeks

Reassess wounds weekly.

Benefits

High: Reduced musculoskeletal and joint pain; slowed childhood nearsightedness progression

Medium: Accelerated wound and skin healing; hair regrowth in pattern hair loss; prevention of cancer-treatment oral mucositis

Low: Muscle recovery and exercise performance; skin rejuvenation and photoaging

Speculative: Cognitive support and brain aging; metabolic and mitochondrial longevity effects

Contraindications

Active or suspected skin cancer in the treatment area

Eye-directed protocols without professional supervision

Direct abdominal or unsupervised use during pregnancy

Key Interactions

Photosensitizing prescription drugs (doxycycline, tetracycline, ciprofloxacin, isotretinoin, amiodarone, some diuretics)

OTC photosensitizers (topical retinoids, alpha-hydroxy acids, benzoyl peroxide)

St. John's wort

Risk & Side Effects

Low: Ocular injury from direct or improper eye exposure; skin burns, redness, and heat discomfort

Speculative: Photosensitivity reactions with light-sensitizing agents; theoretical stimulation of pre-existing malignancy

Monitoring

Marker	Target	Why
hs-CRP	< 1.0 mg/L	Tracks systemic inflammation if using light therapy for inflammatory or recovery goals
Fasting glucose	70–90 mg/dL	Relevant only if targeting metabolic effects
Ferritin	30–150 ng/mL (context-dependent)	Iron status relevant to hair-loss workup before attributing regrowth response
Vitamin D (25-OH)	40–60 ng/mL	Supports skin, hair, and immune goals often pursued alongside light therapy

Cadence: Pain and function every 2–4 weeks during a musculoskeletal course; wounds weekly; hair, skin, or myopia outcomes at roughly 3–6 month intervals.

Qualitative Assessment

Reduction in targeted pain and improved joint or tendon function during daily activities
Visible wound-size reduction and faster healing time
Increased hair density and reduced shedding on serial standardized photographs
Improvements in skin texture, tone, and self-rated firmness
Subjective energy, recovery quality, and (for transcranial use) cognitive clarity, interpreted cautiously given weak evidence

Low-Level Light Therapy for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment