The best full-spectrum infrared saunas

Clearlight puts two 700W True Wave full-spectrum heaters beside the door, facing you, and lines the back wall, side walls and leg area with carbon-ceramic far infrared panels. They're the most powerful single heaters listed for any cabin here, and they supply 1,400W of the 2,500W total. Everything runs from a 13A plug.

At £9,999 you aren't paying for the near infrared so much as the cabin around it: FSC-certified okoume, a glass roof, a limited lifetime warranty for home use, and delivery with installation to most of mainland UK. Clearlight calls its heaters low EMF but gives no figure on the product page.

The weak point of the layout is your back. The full-spectrum heat comes from the front only, and the panels behind you are far infrared, where Hekla puts full-spectrum heaters in front and behind.

Hekla gives full spectrum the biggest role of any two-person cabin here: 2 full-spectrum heaters on the front at 350W each and 2 on the back at 400W each, 1,500W of the 2,400W total, or 63%. Carbon panels cover your sides and a carbon heater sits by the bench. So you get the more intense heat on your back as well as your front.

At £3,599, the full-spectrum layout costs £6,400 less than the Clearlight's. You give up the lifetime warranty (Hekla's is 2 years) and the installation, which costs £249 here or £99 for kerbside delivery only.

You also give up some height. Hekla wants 50cm clear above the 200cm cabin, so you need a ceiling of about 2.5m.

The one-seat Hekla keeps the idea and halves the full-spectrum heaters: one 350W heater in front and one 400W heater behind, with 3 carbon heaters for your sides and legs. Full spectrum makes up 750W of the 1,500W. In a cabin 100cm wide, you sit close to all of it.

At £2,999 it's the cheapest cabin here with full-spectrum heaters both in front and behind. It shares the 130's 2-year warranty and its £99 or £249 delivery choice.

It also shares the need for about 2.5m of ceiling. Its 1.25m² footprint is bigger than some one-person cabins, so measure before you order.

The Sanctuary 1 Pro uses the same two 700W full-spectrum heaters as the two-person cabin in a body 24cm narrower. That makes 1,400W of its 2,160W full spectrum, about 65%, the highest share on this page, and it runs from a 13A plug.

That's the case for it. The case against is £8,999 for one seat: £6,000 more than the Hekla 100 and only £1,000 less than the two-person Sanctuary 2.

You do get the lifetime warranty for home use and installation included, which matters more on a cabin you'll use daily for years. Like the Sanctuary 2, its full-spectrum heaters sit by the door.

£2,803 for two people, in Canadian hemlock, on a 2,500W plug-and-play supply. Pro-Line Direct describes the heat as infrared carbon heaters plus full-spectrum light emitters, with an 18 to 65°C range and a 1 to 99 minute timer. At 150cm wide it's roomy for the money.

It doesn't say how the 2,500W splits between the two types, or where the full-spectrum emitters sit, so you can't compare it heater for heater with the Hekla or Clearlight. The same seller's far infrared two-person cabin is £640 cheaper.

Expect a wait. The listing's estimated delivery runs from 3 November to 1 January.