Sleeping Mat

Ground insulation comes before padding

A sleeping mat does two jobs, and the one that decides the night is rarely the one buyers think about first. Its opening task is to keep a body off cold ground, because insulation squashed flat under a hip stops holding air, and soil pulls heat from a sleeper far faster than still air does. Cushioning is the second task. This range runs from folding foam and small insulated sit mats through self-inflating designs to inflatable single and double pads.

Which type of sleeping mat suits which trip?

Closed-cell foam rolls or concertinas, cannot puncture and shrugs off gravel, but it is bulky and usually rides strapped outside a pack. Self-inflating designs hold open-cell foam behind a valve: open it, the foam expands and draws air in, and a couple of breaths firm it up. Air pads fold down smallest and lift a sleeper highest off the floor, on condition that a repair patch stays within reach. Whatever the fill, the mat handles the cold coming from below and the sleeping bag handles the rest.

What size and thickness are worth choosing?

• Length: shoulders to hips is the working minimum, and anything shorter leaves calves on the ground, which a folded jacket can cover.
• Width: a narrow pad tips when a sleeper rolls and elbows land on soil, so side sleepers gain more from width than from extra depth.
• Thickness: more air between hip and floor means more insulation and more clearance over roots and stones.
• Packed size: foam packs by volume, air pads pack by fold, and both should be measured against the rucksack rather than the boot of a car.
• Valve: a wide twist valve empties in seconds, while a small push valve asks for patience and a knee.

Camp-based sleeping, where a pack is carried from a car park rather than over a ridge, is the territory of the thicker self inflating mattress.

How should a mat be inflated and stored?

Breath carries moisture, and moisture inside a pad eventually smells and adds weight, so a pump sack or short puffs are kinder than long lungfuls. Inflate firm, then let a little air out until a hip just clears the floor under body weight. Between trips, self-inflating pads keep their loft if they sit unrolled with the valve open rather than compressed in a stuff sack for months.

What else is needed for a night on a mat?

Head support is the usual gap, since rolled clothing slides away by two in the morning, which is what a camping pillow fixes for very little weight. Sleeping under a tarp rather than inside a tent also puts the mat within reach of dew and blown spray, and a bivy bag over the top keeps that moisture off the insulation.

Where do mats give up first?

At the valve seat and along repeated fold lines, not in the middle of a panel. Pitching on a cleared patch, keeping the pad on a groundsheet and varying the fold rather than creasing the same seam every time all add seasons of use. A slow leak is far easier to find at home in a bath of water than at midnight by torchlight.