The Patagonia sleeping bags will go on sale this month

Some projects take a while to fruition, and a new sleeping bag from Patagonia is a case in point.

The brand’s founder Yvon Chouinard made himself a simple, mummy-style bag 45 years ago. And it has taken more than four decades for the company to come up with its first production sleeping bags.

The two versions of the Down Sleeping Bags are rated at -1C and -7C and feature a central front zip that allows climbers to tie themselves in at belays or cook more easily at bivvies. The bags feature over-stuffed channels.

They also come in two different sizes.

Patagonia said it has learned a few things in the intervening years. “Materials, design, construction, field-testing – these state-of-the-art practices developed over the life of our company combine to make Patagonia’s down products the most trusted anywhere. Now we’re making a down sleeping bag.”

Both models feature 850-fill traceable down, 15-denier y-yarn nylon shell and durable 15-denier ripstop linings. The -7C bag has a differential baffle construction while the -1C bag has stitch-through construction.

The short -1C version will accommodate a 5ft 6ins (1.68m) sleeper and retails at £360. The regular is for users up to 6ft (1.83m) and costs £380 while the long £400 bag can be used by people up to 6ft 6ins (1.98m).

The respective prices for the -7C model are £500, £500 and £520.

Yvon Chouinard said: “I like the mummy-style bags because they are so simple. I turn around a lot when I sleep and other bags get all twisted in the hood area. Not this one.

“Most bags are under-stuffed. They have great loft when they have great loft – when they’re brand new. But they soon go flat in humid conditions.

“Also, every time you turn around, because there’s not much density, the heat leaks out.”

The new sleeping bags will go on sale in the UK from 22 March.