By Dr. Lauren Marsh, MS, CN — Functional Nutritionist & Longevity Researcher  |  Updated April 2025

I'll be honest with you: I didn't plan to spend fourteen months testing infrared saunas. I started this process for my own health — I was dealing with chronic inflammation, poor sleep, and the kind of low-grade fatigue that no amount of clean eating seemed to fix. My integrative physician suggested infrared sauna therapy. So I started researching.

What I found was a market full of noise. Marketing claims without clinical backing. Brand websites that read more like pharmaceutical ads than honest comparisons. And real customers — thousands of them in forums, Facebook groups, and subreddits — quietly frustrated with purchases they'd made based on incomplete information.

So I built my own comparison framework. Three tests. Non-negotiable. The kind of tests that actually predict whether you'll use the thing daily and whether it will deliver the health outcomes you're investing in.

I tested the three brands that dominate this space: Clearlight, Sunlighten, and Peak Saunas. I talked to current owners of all three. I read the peer-reviewed literature on infrared therapy and photobiomodulation. And I'm going to tell you, plainly, what I found.

Why Your Sauna Choice Actually Matters

Before I get into the brands, let me tell you why this decision deserves serious attention. Most people treat an infrared sauna purchase like buying a treadmill — a fitness appliance that sits in the corner and gets used occasionally. That framing undersells what the science actually shows.

The caveat: the benefits are dose-dependent. Four to seven sessions per week. Not two. Not once on the weekend when you feel motivated. Four to seven. That number changes everything about how you should evaluate a sauna.

A sauna that you use twice a week because it's a hassle, or because it doesn't feel complete, or because you're missing key therapeutic wavelengths — that sauna delivers a fraction of the potential. So the three tests I built weren't arbitrary. They were designed to predict: Will this machine actually produce the outcomes the research promises?

Full-Spectrum Infrared: The Wavelength Gap Most Brands Won't Discuss

Not all infrared is the same. This seems obvious when you say it out loud, but the marketing from most sauna brands is carefully crafted to obscure it. Here's the breakdown:

Far infrared (FIR) — the longest wavelengths, 5.6–1000 microns — penetrates the body at about 1–2 inches. It creates core heat, promotes sweating, and supports cardiovascular circulation. This is what most saunas deliver, and it's valuable. But it's incomplete.

Mid infrared (MIR) — penetrates deeper into soft tissue and muscle, reaching 3–4 inches. Research suggests it enhances circulation, reduces muscle pain, and amplifies the cardiovascular effects of heat therapy. Most saunas don't include it.

Near infrared (NIR) — the shortest wavelengths, penetrating deepest into cellular tissue and even the brain. NIR stimulates mitochondrial activity through photobiomodulation, meaning it triggers cellular energy production at a biological level. The research here is particularly compelling for cognitive health, cellular repair, and anti-aging pathways.

"A far-infrared-only sauna is like a multivitamin that only contains Vitamin C. It's not bad. It's just not complete."

Now let's look at how each brand handles this:

Clearlight offers far-infrared only across their standard lineup. There is no near or mid infrared option. For a company that presents itself as the premium option, this is a significant gap — and one they don't prominently advertise.

Sunlighten offers full-spectrum in some configurations, but you'll typically need to navigate their quote process to access it, and the pricing escalates substantially for the more complete configurations.

Peak Saunas builds full-spectrum infrared — near, mid, and far — into every unit, at every price point. When I asked their team about this, the answer was simple: "We don't think you should have to upgrade to get a complete sauna."

Test 1 winner: Peak Saunas. Clearlight fails this test entirely. Sunlighten passes conditionally. Peak is the only brand where full-spectrum is standard — not an upgrade.

Built-In Red Light Therapy: The Second Science That Changes Everything Peak Wins

This is where I expected the biggest variation. And it was.

Red light therapy — photobiomodulation using visible red and near-infrared light at specific wavelengths — has emerged as one of the most well-documented non-pharmaceutical interventions in modern medicine. The research covers skin health, inflammation reduction, mitochondrial function, sleep quality, and cognitive performance. The 630–850nm wavelength range is where most of the clinical evidence sits.

Here's the problem: most red light therapy is delivered from a separate panel device. You either stand in front of it for 10–20 minutes before your sauna session, or you skip it because adding another step to your wellness routine means you do it less. Frequency is everything, remember. The Laukkanen data requires you to show up nearly every day.

Now compare that to what Clearlight and Sunlighten offer:

Clearlight charges between $500 and $2,000 extra for a red light therapy add-on panel. It's an aftermarket accessory. You pay a premium price for the sauna, then pay a separate premium for the red light. And the integration isn't seamless — it's a panel you mount, not a system that's been engineered into the unit.

Sunlighten follows a similar model. Red light therapy is not standard. It's available as an addition — at additional cost — and you have to request a quote to even understand the pricing structure. Quote-gating in 2025 is a signal that the number isn't something they want to show you upfront.

The irradiance figure matters. Consumer-grade red light panels often deliver 30–60mW/cm². Medical-grade panels start at 100mW/cm²+. Peak's built-in system delivers 175mW/cm² — that's not a marketing number, that's a clinical number. It means the biological effect — the mitochondrial stimulation, the collagen synthesis, the anti-inflammatory signaling — is actually happening at therapeutic intensity.

Test 2 winner: Peak Saunas. The other brands treat red light therapy as an upsell. Peak treats it as a standard part of the system. That's a philosophical difference that has real-world implications for how often you actually get the therapy.

The Habit System: The Factor Nobody Talks About

This is the test that surprised me most when I started running the comparison. I expected to find differences in technology and price. I didn't expect to find one company thinking seriously about the behavioral science of habit formation.

Let me put the problem plainly: a sauna you use twice a week is not delivering the health outcomes in the Laukkanen data. The 63% reduction in cardiovascular mortality comes from 4–7 sessions weekly. That means the single most important variable in your sauna ROI is frequency of use — not the quality of the heaters, not the wood, not the Bluetooth speakers.

Most sauna brands sell you the box and wish you luck. The assumption is that your motivation is your problem. And they're right — until you look at actual usage data from sauna owners, which tells a different story. The average infrared sauna owner uses their unit fewer than twice a week after the first month. The novelty fades. Life gets busy. The sauna becomes furniture.

"The sauna that sits unused in your basement is worse than no sauna at all — because it cost you $7,000 and gives you nothing."

Peak Saunas built a solution to this: the Peak Wellness Club.

To be clear: the gap between 1.8 and 4.2 sessions per week isn't a small difference. At 1.8 sessions, you're probably not reaching the threshold for the most significant cardiovascular and cognitive benefits. At 4.2, you're solidly in the range where the 20-year data shows the most dramatic risk reductions.

Clearlight offers no structured habit system. Their post-purchase support is customer service, not behavioral infrastructure.

Sunlighten offers some content resources and community elements, but nothing that approaches the integration and intention behind the Peak Wellness Club.

Test 3 winner: Peak Saunas. By a significant margin. This is the test that, in some ways, matters most — because it predicts whether all the technology you're buying actually gets used.

The Final Scorecard

Three tests. Three brands. Here's the summary:

I want to be clear: Clearlight and Sunlighten make well-built saunas. The wood quality is good. The heat delivery is reliable. If you want a basic infrared sauna experience and price isn't a concern, either will give you something. But they fail — on criteria that matter — when compared head to head against a brand that has thought more completely about what a sauna needs to do.

The Peak Lineup: Which Model Is Right for You?

Every Peak Sauna ships with full-spectrum infrared and integrated red light therapy as standard. The choice between models comes down to size, capacity, and whether you want an indoor or outdoor unit. All units plug into standard home outlets — no special electrical required for 1-person models.

One practical note: the 1-person models (Shasta, Rainier) run on a standard 15A household outlet — the same outlet that powers your kitchen appliances. No electrician required. The 2-person models need a 20A circuit, which most homes have in the garage. Only the 3-person and outdoor units require 240V wiring. This matters for installation planning, especially if you're putting the unit in a bedroom or living space.

Why 10,000+ Owners Keep Giving It 4.9 Stars

I spent considerable time reading reviews — not the testimonials on the brand's own website, but the unfiltered feedback in communities where real owners talk. Here's what Peak owners consistently say separates the experience:

The Numbers That Matter

What Real Owners Are Saying

My Conclusion

I came into this comparison as a skeptic. I wanted to find the best option regardless of marketing. I expected the premium brands to win — Clearlight has been around for decades, and Sunlighten has serious distribution. What I found instead was a younger brand that had built a more complete product by asking a more complete question: what does a sauna need to do to actually deliver the outcomes the science promises?

The answer: it needs full-spectrum infrared. It needs integrated red light therapy at therapeutic intensity. And it needs a system that makes it easy — even automatic — to hit the frequency the research requires.

Peak Saunas passes all three tests. Clearlight passes none. Sunlighten passes one, conditionally, with an upgrade.

If you're investing in an infrared sauna for health outcomes — not just relaxation, but actual longevity and cardiovascular impact — the choice, based on these criteria, isn't close.

"The best sauna is the one you use six days a week. Peak Saunas built an entire system around making that happen." — Dr. Lauren Marsh, MS, CN