Why Do My Oxygen Levels Decrease After Infrared Light Therapy?

Updated July 2026.

Quick Answer

I didn't find published studies showing near infrared light therapy routinely lowers arterial oxygen saturation (SpO₂) in healthy people. Most photobiomodulation research instead focuses on tissue oxygenation, circulation, mitochondrial function, and related physiological effects. 

If your pulse oximeter reading drops after treatment, the most likely reason is that the heat, increased blood flow, or changes in skin temperature temporarily affected how the pulse oximeter measured your oxygen saturation.

Other possible explanations include:

• Pulse oximeter variability
• Warm skin and increased blood flow
• Relaxation and slower breathing
• An underlying medical condition

Every once in a while a customer asks me a question that sends me down a rabbit hole. This was one of those questions.

Recently, one of our customers wrote to ask:

"My oxygen saturation decreases after NIR-A near infrared light therapy. Is this typical?"

At first, I was stumped.

That doesn't seem to make much sense. After all, one of the most commonly reported effects of red and near infrared light therapy is improved circulation and oxygen delivery to tissues. So why would a pulse oximeter show less oxygen after a treatment?

I decided to dig into the research.

As always, I should mention that none of us here at RubyLux (including me, the owner) are physicians. This article is for educational purposes only and should never replace medical advice from your healthcare provider.

The interesting thing is this:

I could not find any published studies showing that near infrared light therapy routinely lowers arterial oxygen saturation (SpO₂) in healthy people.

That doesn't necessarily mean the customer's pulse oximeter was wrong. 

Let's figure this out, starting at the beginning.

How Does a Pulse Oximeter Measure Oxygen?

Most people think a pulse oximeter somehow measures the amount of oxygen floating around in your blood. It actually doesn't.

Instead, it shines two different colors of light - one red (around 660 nm) and one infrared (around 940 nm) - through your fingertip or earlobe. Hemoglobin carrying oxygen absorbs those wavelengths differently than hemoglobin that has already released its oxygen. The device measures those differences and estimates what percentage of your hemoglobin is carrying oxygen. That's your oxygen saturation, usually abbreviated SpO₂.

Healthy people generally have readings between 95% and 100%.

One important thing to understand is that pulse oximeters don't directly measure how much oxygen your body is using. They estimate oxygen saturation using light passing through your tissues. Because of that, they can sometimes give inaccurate readings.

The FDA notes that pulse oximeter readings can be affected by factors such as poor circulation, skin temperature, movement, darker skin pigmentation, nail polish, artificial nails, tobacco use, and improper placement of the device.

Could Near Infrared Light Therapy Affect the Pulse Oximeter Reading?

I think it's likely that a hot near infrared bulb could interfere with a pulse oximeter reading temporarily. Here's why.

Near infrared light therapy is known to increase blood flow through vasodilation, meaning blood vessels widen. And if you're using a hot incandescent near infrared bulb like the RubyLux NIR-A Near Infrared Bulb, your skin also becomes noticeably warmer.

Those are exactly the kinds of changes that alter the conditions under which a pulse oximeter makes its measurements. In other words, the treatment may not actually be lowering your oxygen saturation at all. It might just be making the measurement less accurate for a short period afterward.

If you've ever taken your oxygen saturation reading multiple times in a row, you've probably noticed that it naturally fluctuates a point or two anyway.

For that reason, I wouldn't be overly concerned about a small temporary drop unless it is accompanied by symptoms.

Could Your Cells Be Using More Oxygen Due to Near Infrared Exposure?

One of the best-supported theories of how photobiomodulation works is that it stimulates an enzyme inside mitochondria called cytochrome c oxidase.

Think of mitochondria as the power plants inside your cells. When they're stimulated by certain wavelengths of red and near infrared light, they often produce more ATP, the molecule your cells use for energy. Researchers believe this is one reason photobiomodulation may help support normal healing, tissue repair and cellular function- cells get energy they didn't otherwise have. They then are able to complete more functions. 

Since mitochondria use oxygen to make ATP, it would seem logical that cells might temporarily consume more oxygen after light therapy. 

But here's where I realized my original 2018 explanation probably wasn't correct. Back then, I suggested that oxygen leaving the bloodstream to enter cells might temporarily lower oxygen saturation. The more I learned about how pulse oximetry works, the less convincing that explanation became.

A pulse oximeter measures arterial oxygen saturation. Healthy lungs are constantly reloading hemoglobin with oxygen.

Even during strenuous exercise, when your muscles consume much more oxygen than they do at rest, most healthy people still have oxygen saturations of 95 to 100%.

If a brisk walk around the block usually doesn't make your oxygen saturation fall, it's unlikely that photobiomodulation alone would cause a significant drop in arterial oxygen saturation.

That doesn't mean tissues aren't using more oxygen. It just means your lungs can keep up.

What About Carbon Dioxide?

During mitochondrial respiration, oxygen accepts electrons at the end of the electron transport chain and is converted into water, not carbon dioxide.

The carbon dioxide we exhale mainly comes from earlier steps in cellular metabolism, particularly the citric acid (Krebs) cycle.

None of this really changes the overall idea that photobiomodulation may increase cellular metabolism.

Could Relaxation Lower Oxygen Saturation?

Here's another possibility we should consider: near infrared light therapy is relaxing. Like, really relaxing.

Some people even fall asleep during treatments. (That's why you need your timer!)

When you're deeply relaxed, your breathing often slows naturally.

For healthy people, that's no problem.

However, someone with:

• sleep apnea
• COPD
• obesity hypoventilation syndrome
• asthma
• certain neuromuscular disorders

may experience a small temporary decrease in oxygen saturation simply because they're breathing more slowly or more shallowly during treatment.

In that situation, the light itself wouldn't necessarily be causing the oxygen drop.

It would be creating a relaxing environment where the person's underlying condition becomes more noticeable.

What Does the Research Actually Show?

One thing I wanted to be careful about while researching this question was separating tissue oxygenation from blood oxygen saturation. They sound similar, but they are not the same thing.

Blood oxygen saturation (SpO₂) is what your pulse oximeter measures.

Tissue oxygenation refers to how much oxygen is actually reaching and being used by your muscles, skin and other tissues.

Most of the photobiomodulation research focuses on tissue oxygenation, not oxygen saturation measured with a fingertip pulse oximeter.

In fact, many studies suggest the opposite of what you might expect from reading that customer's email.

Researchers have reported improvements in:

• microcirculation
• tissue oxygenation
• blood flow
• nitric oxide release
• mitochondrial function

following red or near infrared light therapy.

That doesn't mean every study agrees or that every person responds the same way. But taken as a whole, the research suggests that photobiomodulation generally helps tissues receive and utilize oxygen, rather than depriving them of it.

Nitric Oxide May Be Part of the Story

One interesting effect of near infrared light therapy is its interaction with nitric oxide. Nitric oxide is a tiny signaling molecule your body naturally produces. One of its jobs is relaxing the smooth muscle surrounding blood vessels.

When blood vessels relax, they widen. Then more blood can reach the tissues.

Researchers believe one reason photobiomodulation works is that it temporarily causes nitric oxide to separate from cytochrome c oxidase inside mitochondria. Once released, nitric oxide can help increase blood flow while also allowing the mitochondria to resume making ATP more efficiently.

Think of it like opening more lanes on a highway. Instead of traffic slowing down, blood can move through the tissues more easily.

That makes it even harder to explain why oxygen saturation might decrease after treatment in a healthy person.

Could Your Pulse Oximeter Simply Be Wrong?

Pulse oximeters are handy devices, but they're far from perfect. So what if your oximeter just sucks?

The FDA has repeatedly pointed out that many factors can influence their accuracy. For example, any of these could change the reading:

• Cold hands
• Warm hands
• Movement
• Poor circulation
• Nail polish
• Artificial nails
• Bright outside light
• Darker skin pigmentation
• Poor placement on the finger

If you check your oxygen saturation immediately after sitting in front of a warm near infrared lamp for twenty minutes, you've changed several of those variables at once.

Personally, if I wanted to know whether my oxygen saturation was really decreasing, I'd probably try this experiment:

Take three readings before using light therapy or near infrared sauna.

Wait a minute between each one.

Average the results.

Then repeat the process five or ten minutes after treatment.

If the average consistently drops several percentage points over multiple days, that would be much more convincing than a single isolated reading.

What If Your Oxygen Saturation Really Is Falling?

Let's assume for a moment the pulse oximeter is accurate. What then?

At that point, I think it's much more likely that the light is revealing an underlying problem than causing one.

For example, someone with sleep apnea may become so relaxed during treatment that they begin breathing more shallowly or even fall asleep.

Someone with COPD may have less reserve than a healthy person.

Someone with heart or lung disease might simply notice changes that most healthy people never would.

In those situations, the pulse oximeter may simply be uncovering something that deserves medical evaluation.

When Should You Talk to Your Doctor?

A brief fluctuation of one or two percentage points on a pulse oximeter usually isn't alarming by itself.

However, I would recommend speaking with your doctor if:

• your oxygen saturation repeatedly falls below your normal baseline,
• it stays low after treatment,
• you develop shortness of breath,
• you feel dizzy,
• or you experience chest pain. 
  

One thing I've always believed about red light therapy is that it should make you feel better, not worse.

If something consistently makes you feel worse, it's worth finding out why before continuing. And don't forget that you should immediately discontinue use until you can get help from your doctor. That is one big reason RubyLux accepts returns for any reason. 

So...Is This Normal?

Based on everything I've been able to find, I think one or more of these explanations are the most likely:

• Temporary changes in blood flow affecting the pulse oximeter
• Heat and vasodilation changing the measurement
• Slower breathing during relaxation
• An underlying medical condition
• Normal variation in pulse oximeter readings

Could future research prove otherwise? Absolutely.

Although RubyLux has been in this business longer than almost anyone else, red light therapy is still a relatively new technology, and we're learning new things all the time.

If researchers eventually discover another mechanism, I'll happily update this article again.

The Bottom Line

One of the things I enjoy most about running RubyLux is hearing from customers. Sometimes they have questions that send me digging through dozens of research papers looking for an answer, like this time. I love a good question!

While I didn't find evidence that near infrared light therapy routinely lowers oxygen saturation in healthy people, I did find several reasonable explanations for why someone might see a temporary decrease on a pulse oximeter.

The good news is that the current body of research generally suggests near infrared and red light therapy support healthy circulation, mitochondrial function and tissue oxygenation.