Sunlighten Signature IV Far-Infrared Sauna

After months of research, I finally purchased a Sunlighten sauna and it was one of the best decisions I've ever made. A well-made sauna will last a decade if not longer and provide many health benefits. I use my sauna several times a week to get into a state of deep relaxation for mental health, meditation, and healing.

If you're researching a sauna of your own, take a look at my buyer's guide for the most important things to consider when buying a sauna.

Research process

Only a year ago I knew nothing about saunas but I was fortunate to find a local spa that had unlimited sauna usage for an affordable amount each month. I took the opportunity and spent several months renting out their sauna almost every day.

This knowledge was valuable in helping me determine my preferences and what qualities I wanted when I made my inevitable purchase. Financially, it makes sense to pay for the research upfront when you consider the purchase price of a new sauna is in the thousands of dollars.

The spa I went to had a newer "full spectrum" Sunlighten 2-person sauna and an older far-infrared model. After using these Sunlighten saunas I also sought out their main competitor, Clearlight, and used one of their models too.

Sauna impressions

Before using a Sunlighten I'd heard from several commentators online that they had great build quality, and I can confirm that's the case. Both the interior and exterior have a beautiful design, with quality wood finishing, stylish (and comfortable) heater grill designs, and uncomplicated control panels.

Personally, I wasn't looking for anything complicated, just a simple wooden far-infrared sauna and that's what this is. Except it does have a few perks – on this larger model they have an exterior button which allows you to start the sauna without stepping inside. But the biggest perk is the bench that has a foldable knee and backrest so you can stretch out in comfort.

Assembly was straightforward, although you will need 2-3 people minimum to lift the sides and roof into place. I went with the basswood wood paneling and didn't detect any odors, however, there were a few unsanded edges. The floor does get dirtier than I expected after repeated use and the inset floor heater collects dust and debris that need to be cleaned on occasion.

Video walkthrough


This is a quick summary of important specifications. Please consult the Sunlighten website for a more detailed description.

  • Control panels – Interior control panel for temperature, time, and interior / exterior lighting. There is also an exterior button for turning on or off the device without having to get in.
  • Sound system – Two Blaupunkt speakers in the ceiling with a stereo built into the cabin that offers a radio antenna, auxiliary cord input, Bluetooth, and USB port.
  • Weight – Roughly 700 pounds and requires at least 2-3 people to assemble.
  • ElectricalDedicated 240V 20A circuit and outlet required (NEMA 6-20R). A ground fault interrupter (GFI) is built into the sauna. 9-foot cord exits from the back left of the roof.
  • Exterior – 80.9" W, 56.1" D, 78" H
  • Interior – 74.4" W, 49.9" D, 70.3" H
  • Interior bench– 74.4" W, 20" D, 19" H

Heat-up time

Despite its large size, I've been impressed by how fast this sauna heats up. I keep my sauna in my garage where the ambient temperature is around 80 degrees and after a 30-minute heat-up time it's already at 120 degrees. So my estimate is roughly one degree per minute.

To measure this, I recorded the heat-up times of six different sessions in the sauna. See below for the combined results which show a trend of 1.1°F per minute.

Sunlighten Signature IV heatup time measurements.
Average heatup time over six sessions.

Sales experience

Early on in my research process I gave Sunlighten a call to inquire about their prices. I will say that they were friendly and helpful in telling me about their saunas. However, I regretted calling because they were pretty aggressive in calling me back week after week to close the sale.

A sauna is a big purchase so I was taking my time learning as much as I could about different manufacturers and models. So for one sauna company to repeatedly call me back when I wasn't ready to purchase felt a bit "sales-y" to me.

It also annoyed me that the salespeople would make statements like how their heaters "are the only far-infrared heaters clinically shown to raise core body temperature ... lower systolic and diastolic blood pressure, and aid in weight loss." This is repeated in claims on their website.

While I don't doubt that the research was done, I find it meaningless when deciding which sauna to buy. Every company is desperate to differentiate themselves in the market, but any well-made sauna will raise body temperature, and the effects on weight loss and blood pressure are from general sauna use, not something unique to Sunlighten.

Useful accessories

Find yourself some high-quality towels because you will go through more than you can imagine. I regularly bring two towels into a sauna session with me and they are soaked through afterward.

I also found it helpful to have an air purifier in the sauna cabin with me. It can get steamy inside with evaporated sweat, and while it never smells I do wonder what that sweat might contain. A small HEPA filter would work great, but right now I'm just using a Moso activated-charcoal bag to combat any gases or odors that might occur.

While activated carbon cannot remove fine particles from the air (use a HEPA filter for that) it is effective at removing gases like volatile organic compounds (VOCs) which are released in sweat or as part of the glue used in the sauna manufacturing process.[1]

You will need an electrician

Due to the high power consumption of this sauna, you will need to hire an electrician to install a 20 amp dedicated circuit. Most of the outlets in your house will be 15 amp (a measure of the electrical draw/usage of the device) except for your washing machine, oven, and other large appliances.

Also, most outlets in your house share the same circuit. That's why if you blow a circuit breaker by using a hairdryer, for example, it might disable the entire bathroom. You will need a "dedicated" 20 amp circuit which simply means that the sauna will be the only device on that circuit.

Final thoughts

I've had my sauna several months now and I continue to be extremely happy with my purchase. I see the sauna as an important health tool – a piece of equipment that can put me in a deeply relaxed state or to keep my sweating and invoke a cardiovascular response on a recovery day.

Despite the high price tag, I'm reassured by the long warranty and the fact that there isn't much wear and tear over time. I'm confident it will last another decade at least.