Red Light Therapy for Circulation & Blood Flow

Poor circulation affects millions of people in the UK, from the cold fingers and toes of Raynaud’s phenomenon to the serious cardiovascular consequences of peripheral arterial disease and hypertension. The mechanisms linking red light therapy to improved blood flow are among the most well-characterised in photobiomodulation research — and the clinical implications extend far beyond warmer extremities.

This page examines the evidence for red light therapy’s effects on circulation, blood pressure, and cardiovascular health. The science here is genuinely compelling, grounded in well-understood biochemistry and supported by human clinical data.

How red light therapy improves blood flow

The nitric oxide mechanism

The primary pathway through which red and near-infrared light improve circulation involves nitric oxide (NO) — one of the most important signalling molecules in vascular biology. Robert Furchgott, Louis Ignarro, and Ferid Murad shared the 1998 Nobel Prize in Physiology or Medicine for discovering nitric oxide’s role as a vasodilator.

Red and near-infrared light release nitric oxide through two distinct mechanisms:

1. Dissociation from cytochrome c oxidase. Nitric oxide binds to cytochrome c oxidase (Complex IV of the mitochondrial electron transport chain) and inhibits cellular respiration. When red or near-infrared photons are absorbed by cytochrome c oxidase, they photodissociate the bound NO, releasing it into the cell and surrounding tissue. This simultaneously restores mitochondrial function (by removing the NO inhibition) and provides a burst of free nitric oxide (Karu et al., 2005, Photochemistry and Photobiology, 81(4), 1047-1053).

2. Release from haemoglobin and myoglobin. Both haemoglobin and myoglobin carry nitric oxide in the blood. Red and near-infrared light can release this stored NO, increasing local concentrations. Lohr et al. (2009) demonstrated that 670nm light released nitric oxide from haemoglobin both in vitro and in vivo, producing measurable vasodilation (Free Radical Biology and Medicine, 47(8), 1150-1158).

Once released, nitric oxide diffuses into the smooth muscle cells that line blood vessels and activates an enzyme called soluble guanylate cyclase, which produces cyclic GMP. Cyclic GMP causes the smooth muscle to relax, the vessel dilates, and blood flow increases.

This is not speculative biochemistry — it is the same mechanism targeted by nitroglycerin (used for angina since 1879) and sildenafil (Viagra). Red light therapy achieves a similar end result through a different delivery mechanism.

Endothelial function

Beyond the acute release of nitric oxide, red light therapy appears to improve the long-term health and function of endothelial cells — the cells that line blood vessels and regulate vascular tone, permeability, and inflammation.

Endothelial dysfunction is a hallmark of cardiovascular disease, hypertension, diabetes, and ageing. It is characterised by reduced nitric oxide bioavailability, increased oxidative stress, and a pro-inflammatory, pro-thrombotic state.

Sarandol et al. (2021) demonstrated that photobiomodulation reduced markers of endothelial dysfunction including asymmetric dimethylarginine (ADMA) — an endogenous inhibitor of nitric oxide synthase. By reducing ADMA levels, red light therapy may increase the body’s own capacity to produce nitric oxide, leading to sustained improvements in vascular function rather than merely acute vasodilation.

Angiogenesis

Red light therapy promotes the formation of new blood vessels (angiogenesis) through upregulation of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF). This has been demonstrated in wound healing studies where increased capillary density in treated areas is consistently observed (Chung et al., 2012, Annals of Biomedical Engineering, 40(2), 516-533).

For chronic circulatory conditions, the formation of new capillary networks could provide meaningful long-term improvements in tissue perfusion — particularly in areas where the existing vasculature is compromised.

Clinical evidence

Peripheral blood flow

Mitchell and Mack (2013) conducted a controlled study examining the effects of 670nm red light on forearm blood flow in healthy subjects. Using venous occlusion plethysmography, they measured a significant increase in forearm blood flow following a single 30-minute treatment session. The effect persisted for at least 30 minutes after treatment cessation.

Samoilova et al. (2008) studied the effects of polychromatic light (480 to 3400nm, including red and near-infrared wavelengths) on microcirculation using laser Doppler flowmetry. They found a 40 to 60 per cent increase in microcirculatory blood flow that peaked 15 to 30 minutes after treatment (Photomedicine and Laser Surgery, 26(2), 111-118).

Raynaud’s phenomenon

Raynaud’s phenomenon — characterised by episodic vasospasm of the digital arteries, causing fingers and toes to turn white, then blue, then red — is a condition where improved vasodilation should provide direct symptomatic relief.

Al-Watban and Andres (2001) investigated the effects of low-level laser therapy on peripheral blood flow and found that 632.8nm laser irradiation significantly improved digital blood flow in subjects with compromised peripheral circulation (Photomedicine and Laser Surgery, 19(6), 437-442).

Whilst there are no large-scale RCTs specifically examining red light therapy for Raynaud’s, the mechanism is straightforward: NO-mediated vasodilation counteracts the excessive vasoconstriction that defines the condition. Individual case reports and small studies consistently report improved symptoms, particularly during the recovery (reperfusion) phase.

If you have Raynaud’s, red light therapy is worth considering as a complementary approach alongside cold avoidance, calcium channel blockers (if prescribed), and lifestyle modifications. It is not a replacement for medical management of secondary Raynaud’s associated with connective tissue diseases.

Blood pressure

The relationship between red light therapy and blood pressure is particularly interesting because it follows logically from the nitric oxide mechanism. If red light increases NO bioavailability and promotes vasodilation, a reduction in peripheral vascular resistance — and therefore blood pressure — should follow.

Liebert et al. (2017) conducted a pilot study using transcutaneous photobiomodulation at 904nm and found a statistically significant reduction in systolic blood pressure in hypertensive subjects (Laser Therapy, 26(2), 119-126). The reduction was modest (approximately 10 to 12 mmHg systolic) but clinically meaningful — comparable to the effect of a single antihypertensive medication.

Opländer et al. (2016) demonstrated that whole-body irradiation with broadband UVA light (which also releases NO from skin nitrite stores) reduced blood pressure in a dose-dependent manner (Journal of Investigative Dermatology, 129(12), 2974-2983). Whilst UVA is a different wavelength range from therapeutic red light, the shared nitric oxide mechanism suggests parallel effects.

It is worth noting that sunlight exposure — which includes red, near-infrared, and UV wavelengths — has been consistently associated with lower blood pressure in epidemiological studies. Weller et al. (2020) argued that the cardiovascular benefits of sunlight are mediated substantially through nitric oxide release, not through vitamin D (International Journal of Molecular Sciences, 21(10), 3507).

Important caveat: Red light therapy is not a substitute for prescribed antihypertensive medication. If you are being treated for high blood pressure, continue your medication and discuss any complementary therapies with your doctor.

Heart health and cardiovascular disease

The cardiovascular implications of improved endothelial function and nitric oxide bioavailability extend beyond blood pressure:

• Atherosclerosis. Endothelial dysfunction is the initiating event in atherosclerotic plaque development. By improving endothelial function, red light therapy may have a role in primary prevention — though this remains theoretical and no human trials have tested this directly.
• Post-myocardial infarction recovery. Animal studies have shown that photobiomodulation applied to the chest reduces infarct size and improves cardiac function after experimental heart attacks (Oron et al., 2001, Lasers in Surgery and Medicine, 28(3), 220-226). Human data is limited to case reports.
• Heart failure. Reduced exercise capacity in heart failure is partly attributable to skeletal muscle dysfunction and impaired peripheral blood flow. Red light therapy’s effects on both muscle mitochondria and peripheral circulation could theoretically improve exercise tolerance, but clinical evidence is preliminary.

Recommended protocol for circulation

Wavelengths

• 660nm (red) — Effective for superficial blood flow improvement, skin-level vasodilation, and finger/toe circulation
• 850nm (near-infrared) — Penetrates deeper, reaching larger blood vessels and muscle tissue. Better suited for systemic effects and deep tissue perfusion
• Combined 660nm + 850nm — Ideal for addressing both superficial and deep circulatory benefits

Dosing

• Power density: 20 to 100 mW/cm² depending on device and distance
• Dose per session: 10 to 30 J/cm²
• Treatment time: 5 to 15 minutes per area (depending on device output)
• Frequency: Daily or 5 times per week for active symptoms; 3 times per week for maintenance

Application areas

For general circulation improvement:

• Chest and upper back — Large surface area treatment to influence systemic blood flow
• Extremities — Direct treatment of hands and feet for peripheral circulatory issues
• Major muscle groups — Legs and arms to improve muscular blood flow

For Raynaud’s:

• Direct hand/foot treatment — 660nm at close range, 5 to 10 minutes per hand or foot
• Preventive treatment before cold exposure may reduce the frequency and severity of attacks

For blood pressure:

• Full-body or large-area treatment — Using a panel large enough to treat the torso
• Consistent daily treatment appears more important than individual session duration

Device recommendations

For peripheral circulation (hands, feet, Raynaud’s): A handheld device or small panel allows targeted treatment of extremities. Wraps designed for hands or feet can maintain close contact for consistent dosing.

For systemic circulation and blood pressure: A larger panel (half-body or full-body) provides the coverage needed for systemic effects. The goal is to irradiate a substantial body surface area to maximise nitric oxide release.

For exercise and muscle perfusion: Wraps or pads applied to large muscle groups before or after exercise. See our best body wraps page for options.

The bottom line

Red light therapy’s effects on circulation are among the most well-supported in photobiomodulation research. The nitric oxide release mechanism is well characterised, reproducible, and grounded in Nobel Prize-winning biochemistry. Clinical studies confirm measurable improvements in peripheral blood flow, and the evidence for modest blood pressure reduction is growing.

For Raynaud’s phenomenon, the rationale is particularly strong — direct vasodilation of constricted digital arteries addresses the core pathology. For general cardiovascular health, red light therapy should be viewed as a complement to, not a replacement for, established interventions including exercise, diet, and prescribed medication.

The risk profile is minimal. The biological plausibility is high. And unlike many applications of red light therapy where the evidence is preliminary, the circulatory benefits rest on one of the most thoroughly studied mechanisms in the field.