How Long Does Red Light Therapy Take to Work?

How Does Red Light Therapy Work?

Red light therapy, also called photobiomodulation, works at the level of your cells, specifically in the mitochondria, the parts of your cells that produce energy. Scientists have identified cytochrome c oxidase, an enzyme in the mitochondria, as the main site where red and near-infrared light is absorbed.

The leading theory is that light releases nitric oxide that blocks this enzyme, which allows the mitochondria to produce more ATP, your cells' energy currency. This then triggers signals in the cell linked to repair, anti-inflammatory processes and antioxidant defence.

Why red and near-infrared together? Both are absorbed by the same enzyme, but they reach different depths. Red light acts mainly in the skin and the layers just beneath, while near-infrared travels further into muscle and joint tissue. Combining the two lets one session reach both surface and deeper tissue.

How Long to See Results for Muscle Recovery

Per training session. A systematic review with meta-analysis by Leal-Junior and colleagues looked at phototherapy applied before, during and after exercise, measuring outcomes such as repetitions, time to exhaustion and creatine kinase, a marker of muscle damage. They concluded that it improves muscle performance and speeds up recovery, mainly when applied before exercise. In other words, some effects relate to the session you're recovering from right now.

Over a training block. Longer-term effects take weeks to build:

• In an 8-week randomised trial, a group combining photobiomodulation with blood flow restriction training gained more strength than the placebo groups.
• In a 12-week case study with identical twins following the same strength programme, the twin using LED therapy lifted more, reported less muscle soreness, and showed more thigh muscle growth than his brother on placebo. Interesting, but it's only one pair of twins.

In practice: think in terms of training blocks of 8 to 12 weeks, rather than expecting a dramatic change after one session.

How Long to See Results for Your Skin

Skin works on a slower cycle, because collagen takes time to build. In a randomised controlled trial with 136 volunteers, participants were treated twice a week and evaluated after 30 sessions, about 15 weeks. Compared with the control group, they showed improvements in skin rejuvenation and collagen density. A study of a home-use LED face mask with red and near-infrared light found that participants were satisfied and saw improvements after 6 weeks.

So for skin: expect to commit to at least 6 weeks, and plan for around 3 months for a full picture.

How Long Is a Session?

Most sessions last 10 to 20 minutes, depending on the device. Longer is not better: research shows a clear biphasic dose response, where low doses stimulate and high doses can actually have an inhibitory effect. Always follow the recommended session time for your device.

Want to know how many sessions per week work best? Read our blog on how often to use red light therapy.

How Do You Know If It Is Working?

Because the effects build gradually, it's easy to miss progress. These tips help:

• Track your recovery. Rate your muscle soreness from 1 to 10 the day after hard sessions, and note how quickly you're ready to train again.
• Watch your training numbers. Look for small changes in reps, weights, pace or how heavy your legs feel on back-to-back training days.
• Take photos for skin. Use the same light, angle and time of day, and compare every 4 weeks rather than daily.
• Be consistent. Results in studies come from regular, repeated sessions. Skipped weeks make it hard to judge.
• Give it time. Evaluate after at least 6 to 8 weeks, not after one week.

Red light therapy works best as part of a complete routine with good sleep, nutrition and smart training. If you have ongoing pain or a skin condition, consult a professional.