How to Use Red Light Therapy: Distance, Time and Dose

Stand 15 to 30cm from the panel, expose bare, clean skin over the muscle you want to treat, wear the goggles, and run it for 5 to 10 minutes per area, three to five times a week. That's the short answer for a decent home panel putting out around 100 mW/cm2 at that distance. The longer answer is that "10 minutes" means nothing on its own, because the thing your tissue responds to is dose, and dose depends on how bright your panel really is at the spot where your leg happens to be.

This guide covers the practical side: setting up a session, working out your own numbers, and avoiding the mistakes owners make in the first month. If you want to know whether red light helps recovery at all, our separate piece on red light therapy for recovery goes through the research and the mechanism. Here we'll assume you've bought a panel, or are about to, and want to use it properly.

How to use a red light therapy panel, step by step

1. Clear the skin. Take off clothing over the area, because fabric blocks most of the light. Wash off sunscreen, heavy moisturiser and make-up first; mineral sunscreens especially are designed to reflect light, which is the opposite of what you want here.
2. Put the goggles on. Do this before you switch the panel on, not after. Opaque goggles are fine when you're treating your body; when treating your face, close your eyes as well.
3. Pick your mode. If the panel runs red (around 630 to 660nm) and near infrared (around 810 to 850nm) separately, use near infrared or both together for muscle and joints. Red on its own mostly reaches skin and surface tissue.
4. Set the distance. Measure it once with a tape measure, from the LED face to your skin, and remember it. Most people who say a session "didn't do anything" have no idea how far away they were sitting.
5. Set a timer. Use the panel's own timer or your phone. Work the length out from your panel's irradiance at that distance (see the dose section below) rather than from the marketing.
6. Keep still and face the panel. Point the treated area squarely at the LEDs. Light hitting skin at a steep angle reflects away and covers a smeared, weaker patch.
7. Move to the next area. For a big panel and a whole thigh, one position might be enough. With a compact panel, treat the front and back of the leg as two separate sessions.

You'll feel mild warmth at most. That's normal, and it isn't a sign the treatment is working any better or worse.

Red light therapy distance and time

Distance and time are linked, and that's the bit people get wrong. Move further back and the light spreads over more of your body, but less of it lands on any given square centimetre, so you need longer to reach the same dose. Move closer and you get more intensity on a smaller patch.

The Nebula 1020W is a useful example because Nebula publishes two readings: 95 mW/cm2 at 6 inches and 76 mW/cm2 at 12 inches (the brand's figures, not ours). That's a smaller drop than many people expect, partly because a tall panel lights you from lots of LEDs at once. Small panels lose output faster as you back away, which is why compact units suit knees and elbows held close in.

As a working rule:

Distance	Best for	Typical session on a ~100 mW/cm2 panel
10 to 15cm (4 to 6in)	A single joint, a calf, an elbow	5 to 8 minutes
15 to 30cm (6 to 12in)	A thigh, the lower back, both quads on a tall panel	8 to 12 minutes
30cm+	Whole body front or back on a large panel	10 to 15 minutes, if output holds up at that range

Treat that table as a starting point. If your panel publishes a figure at your exact distance, use the dose calculation below and ignore the table.

What dose actually means

Dose in photobiomodulation is energy delivered per area, measured in joules per square centimetre (J/cm2), and the arithmetic is simple:

Dose (J/cm2) = irradiance (mW/cm2) × time (seconds) ÷ 1,000

So a panel that really delivers 100 mW/cm2 at your skin, run for 10 minutes (600 seconds), gives you 60 J/cm2. Halve the irradiance by standing further back and you need 20 minutes to deliver the same 60 J/cm2. If you want to reverse it, divide the dose you're aiming for by your irradiance, multiply by 1,000, and you've got the seconds.

The catch is that more dose isn't automatically better. Light therapy follows a biphasic response, where the benefit climbs to a peak and then tails off as you keep going, which our recovery evidence guide covers in detail. The trade between power and time isn't perfectly linear either. In a double blind trial comparing three commercial devices, forty untrained men had the same total energy (180 J) applied to the quadriceps after damaging eccentric exercise. The low powered pulsed device protected strength and reduced soreness compared with placebo; the high powered continuous device, which delivered that energy in less time, showed no benefit on strength, creatine kinase or soreness. One study doesn't settle it, but it's a good reason not to assume a brighter panel lets you crank the session down to two minutes.

So don't chase the biggest number. Aim for a moderate dose you can repeat consistently.

Why the mW/cm2 on the box is often too high

If your dose calculation rests on irradiance, the irradiance had better be honest. Often it isn't.

There are a few reasons. Some brands measure with cheap solar power meters designed for sunlight, which tend to over-read near infrared. Others take the reading at the hottest point dead centre of the panel, with the meter almost touching the LEDs, then quote that figure as though it applies everywhere. And plenty don't say what distance the number applies to at all.

Look at how the panels we've covered present it. Nebula gives irradiance at two distances and states a real power draw of 288W. The STASUN 1050W claims over 167.4 mW/cm2, but only at 3 inches, a distance that flatters any panel and one you'll rarely use with something 85cm tall. We haven't measured either with a spectrometer, and that's the point: you're taking the brand's word, so give more weight to brands that show their working. The Flikeze panel is worth reading with the same question in mind.

The practical fix is to assume your panel is somewhat dimmer than advertised and to lean on the longer end of a sensible time range, rather than the shorter one. Ignore the wattage on the box entirely. A "1000W" panel is usually just the number of LEDs multiplied by their rated chip power, and it says nothing about what reaches your skin.

Before or after training?

The evidence splits by goal, and it's more favourable to pre-exercise use than most people assume.

A review of 46 photobiomodulation trials in human muscle, covering 1,045 participants, found that both pre-conditioning (light delivered to muscles before exercise) and light applied afterwards could improve performance, with some studies also reporting more muscle gained after training and lower markers of inflammation. More recently, a 2026 meta-analysis in volleyball and football players pooled 14 randomised trials and found more repetitions before fatigue and lower creatine kinase, but no significant change in maximal strength.

How that translates to you:

• Before a session if your aim is more reps or delayed fatigue. Treat the muscles you're about to work, then start training within roughly half an hour.
• After, or that evening, if soreness is what's holding you back. This is where most of the DOMS research sits.

One caveat runs through all of it. Most of these trials used lasers or LED clusters held against specific points on the muscle, not a panel 20cm away, so the doses don't map neatly onto home use. Use the research to choose your timing, not to copy exact numbers.

How often to use it

Three to five sessions a week works for most people. Match sessions to training: legs after a leg day, shoulders and upper back after pressing. There's no benefit in treating your whole body every day just because the panel's on the wall, and you'll stick with a short, targeted routine for far longer than a 40 minute one.

Give it four to six weeks of regular use before you judge whether it's helping. A single session won't tell you anything.

Eye protection

Wear goggles, even if the panel looks like it's barely on. Near infrared is invisible, so a panel running only 850nm can look dim or almost dark while still putting out plenty of energy, and your eyes get no warning signal to blink or look away.

Use the goggles that came with the panel; if it didn't come with any, buy a pair rated for the wavelengths it uses. Don't look directly into the LEDs while it's running, and switch it off before you take the goggles off. If you have any existing eye condition, have had eye surgery, or take medication that affects light sensitivity, speak to your optometrist or GP before you start, and treat your face only with their go-ahead.

Who should avoid it, or check first

Red light therapy is low risk for healthy adults using it sensibly, but some people should get advice from their GP before using a panel:

• Anyone taking photosensitising medication. That list includes some antibiotics (such as tetracyclines), retinoids like isotretinoin, some diuretics and others; your pharmacist can check yours.
• Pregnant women. There's very little research on use during pregnancy, so the cautious answer is to wait or get medical sign-off, and certainly avoid treating the abdomen.
• People with eye conditions, a history of skin cancer, or active cancer, and anyone with light-sensitive epilepsy if the panel has a pulsing or flicker mode.

Don't shine it over moles that look unusual, and stop if you notice skin irritation, headaches or eye strain after sessions.

Common mistakes

Sitting too far away for too short a time. Ten minutes at 60cm on a mid-range panel can deliver a fraction of the dose you think you're getting.

Doubling the session because you can't feel anything. There's nothing to feel. Longer isn't better past a point, and you can overshoot.

Treating through clothing. Fabric blocks most of the light.

Trusting the box. Wattage is marketing arithmetic, and irradiance quoted at 3 inches or at contact won't hold at the distance you actually use.

Skipping the goggles because the panel looks dim. With near infrared modes especially, dim-looking isn't the same as low output.

Expecting it to replace the basics. Sleep, food and sensible training load do most of the recovery work. Light therapy is a small extra on top, and the rest of the kit that helps sits in our recovery section.

Recommended reads

• Red light therapy for recovery: what the evidence supports
• Nebula 1020W red light therapy review
• STASUN 1050W red light therapy review
• Flikeze red light therapy panel review
• All our recovery guides and reviews