How to sleep well in a tent: mattress types and R-value explained

The cold you feel at 3am in a tent almost never comes through the air above you. It comes up from the ground below, straight through the mattress you bought for comfort, because a mattress full of freely moving air is a very good conductor of your body heat into the earth. That is the mistake most campers make: choosing thickness, which you feel with your hand in the shop, over insulation, which you only feel at 3am. Insulation has a number, and once you know it, tent sleep stops being luck.

Why do you wake up cold on a thick mattress?

Here is the mechanism, because understanding it is what stops you repeating the mistake in a different aisle. Lie on any mattress and your body warms the air inside it. On an uninsulated air bed, that warm air does not stay put: it circulates, touches the cold underside sitting on the ground, sheds its heat, and comes back up for more of yours. The process runs all night, which is why a luxurious 20-centimetre air bed can sleep colder than a thin foam mat whose closed cells trap air in place and stop the circulation. Your sleeping bag cannot rescue you either, because the insulation under your body is compressed flat by your weight and does almost nothing. Whatever is between you and the ground is doing the real work. Ground temperature also lags air temperature, so even after a warm Queensland spring day, the earth you park a tent on can pull heat for hours, and a riverside or beach site adds evaporative chill on top. The fix is never a thicker air column. It is stopping the circulation, which is what insulation means in practice.

What is R-value and how much do you need?

R-value measures resistance to heat flow: the higher the number, the less body heat the ground can pull through the mat. For years every brand measured it differently, which made comparison meaningless. There is now a single test method for it: ASTM F3340, currently in its 2022 revision, which compresses the mattress between a heated plate and a cooled one and measures how much heat crosses it. Because every brand runs the same test, two mats with the same rating insulate comparably regardless of who made them. The practical reading for Australian car camping: mild-season nights on the coast are comfortable on modest ratings, while inland and high-country nights that drop toward single digits want a substantially higher one, and R-values add up, so a foam mat under an air mattress combines both numbers. If a mattress you are considering publishes no R-value at all, treat it as unrated for warmth and plan to add a layer beneath it rather than guessing.

Which mattress type suits how you camp?

Car camping removes the weight penalty that forces hikers into compromises, so the honest question is not which type is best but which failure you least want to live with. Self-inflating mats such as the Often Deluxe self-inflating mattress ($189) are the balanced default: the foam core insulates even if they lose some air overnight. Pure air mattresses win on comfort and lose everything to a puncture at midnight, so they belong with a repair kit and a pump you have tested. A stretcher such as a foldable camp bed gets you off stony or wet ground entirely and turns a tent into a bedroom, with one caveat: in cool weather the air circulating underneath needs a mat on top of the stretcher to block it. The full range of options is in the mattress collection, with listed specifications on each product page.

Couples add one decision: one double surface or two singles. A double mattress feels like home and transmits every movement like home too, so the light sleeper in the partnership inherits the heavy sleeper's turning. Two singles pushed together keep the shared-bed feeling while isolating movement, they let each person choose their own firmness and warmth rating, and they split between vehicles or trips when one of you camps solo. The same logic applies to stretchers, which are singles by nature and make the choice for you. There is no wrong answer, but the two-singles setup fails more gracefully: a puncture or a valve problem strands one sleeper on the spare foam mat instead of both of you on the ground, and redundancy is worth more at midnight than symmetry, a theme this guide keeps returning to because tents have no spare room to fail in.

What about sleeping in a rooftop tent?

A rooftop tent changes the physics in your favour. You are a metre and more off the ground, so the cold, damp earth that dominates ground-tent sleep is out of the equation, replaced by moving air under the floor, which is gentler but not free. Most rooftop tents ship with a built-in foam mattress, and the base they sit on is flat and hard, closer to a slat bed than to dirt, which is why so many people report their first rooftop night as the first real sleep they have had camping. Two upgrades matter if you run one through winter: a thin self-inflating mat on top of the factory foam adds warmth and softness for almost no packed volume, and an anti-condensation underlay lets the mattress breathe so it is not damp when you fold the tent away. Levelling the vehicle before bed does more for sleep quality than any mattress upgrade; two minutes with ramps or a shovel beats a night of rolling downhill.

Condensation deserves its own sentence in the rooftop context. Warm bodies in a small, well-sealed capsule produce moisture all night, it condenses against the cool underside of the mattress and the floor, and a tent folded away damp on Sunday becomes a mouldy tent by the next trip. The anti-condensation underlay creates an air gap that lets the mattress base breathe, cracking a vent on the downwind side keeps air exchanging without a draught, and standing the mattress on its edge for ten minutes with morning coffee finishes the job. None of this costs sleep or money worth mentioning, and together they roughly decide whether the built-in mattress is still pleasant in two years.

How do you set up the bed on a cold night?

Layer from the ground up, in this order: something insulating directly on the floor, your mattress on top of it, then the sleeping bag, and get into it warm rather than expecting the bag to heat you. A hot water bottle filled from the dinner kettle and dropped in ten minutes before you climb in converts the bag from a cold envelope into a warm one, at zero technology cost. Wear dry base layers, never the day's damp shirt, and put tomorrow's clothes inside the bag with you so they are warm at 6am. Eat before sleeping; digestion is heat. And resist sealing the tent airtight: ventilation carries out the moisture you breathe all night, and a dry bag insulates far better than a damp one, which is the same reason we recommend airing everything before pack-down.

Which setup should you buy first?

Start from your worst realistic night, not your average one. Coastal spring and summer trips: a self-inflating mat alone will carry you, and comfort is the only variable worth paying for. Anything inland between autumn and spring: rate for the cold night, which means a published R-value or a foam-plus-air stack, because you can always vent warmth but you cannot create insulation at midnight. Families setting up a base camp for the three-night getaways within reach of Brisbane: stretchers plus mats give everyone a real bed and survive being trampled. If you are assembling your first kit from nothing, the order of spending that pays off fastest is mattress, then pillow, then everything else, because every other purchase merely decorates the trip while these two decide whether you want another one; the rest of that list is in our beginner's guide to camping in Queensland.

And do not let the pillow be an afterthought, because necks do not grade on a curve. A bundled jumper works for exactly one night; after that it is a lump with sleeves. The Chill & Rest range covers the whole sleeping side, pillows included. Bring the pillow from home if space allows, since nothing camp-sized matches it, or choose an inflatable with a brushed face and put a shirt over it for the skin feel. Side sleepers need more height than back sleepers, which is the single spec that matters when comparing camp pillows, and a pillow that slides off the mat all night is solved with a strip of the grippy shelf liner sold in every hardware shop. Small item, outsized share of whether morning two feels like a holiday, and the cheapest fix in this entire guide.