The top bag design of the Thermarest Parsec isn’t for everyone but does give Peter Macfarlane a comfortable night’s sleep.

The Thermarest Parsec has a different construction format from the other sleeping bags in our guide to the Best sleeping bags for hiking and consequently requires a different approach from the user. The Parsec is a ‘top bag’, which means that the hood, the footbox and the rest of the bag from the ground up is a regular sleeping bag but the back – the area that touches the ground – has very little or no insulation at all.

Price: £360 | Weight: 906g (Long) | Materials: 800 fill power hydrophobic, ethically certificated down, nylon shell | Temperature Comfort Limit: -6°C | Features: box wall construction, mummy shape, top bag design, shoulder baffle, full-length two-way zip, external pocket, stuff sack, storage sack | Sizes: Small, Regular, Long | Womens version: Unisex

This saves weight and bulk, and allows you to tune your performance by choosing a sleep mat to cover the missing area of insulation to match the conditions you’ll be camping in.

The sleep mat attaches to the Parsec via the supplied straps or additional bungee cords you can attach to the loops along the underside of the bag. Properly securing the mat gives me a good night’s sleep as I turn and move inside the bag in a natural way just as I would in bed at home. It also stops the uninsulated lower bag being exposed.

The Parsec lofts very well and has a comfortable roomy mummy cut with a well-shaped footbox. The hood is medium in size and has an effective baffle that seals around the top of my head without needing to cinch in the hood, which you can do with external drawcords. There’s a shoulder baffle that isn’t adjustable but is fat enough to still be effective.

The zip is relatively snag-free and the outer shell has decent water repellency.