Your sleeping bag is making you hotter in this heatwave – here's what to use instead, according to a camping expert
You don't need to buy a summer sleeping bag to get a better night's sleep outdoors
Camping in a heatwave sounds idyllic... until bedtime arrives. After a day spent hiking, the inside of your backpacking tent can feel like an oven, and even the lightest sleeping bag suddenly becomes far too warm.
The good news is that you don't necessarily need to invest in a specialist summer sleeping bag (even though they will most certainly help). A few simple changes to your sleep setup can make a dramatic difference, helping you stay cool without sacrificing comfort.
Speaking of staying cool in the tent, make sure you check out our list of hot weather camping hacks, which suggest losing the flysheet and pitching the tent in the shade, among other tips. We also have a roundup of five gadgets that can keep you cool in your tent, in case you're interested.
Matt is T3's inhouse outdoor expert who spent countless nights in tents, bivvies, and other various shelters. He's always ready to go camping, no matter the weather. He's been testing and reviewing all manners of camping gear on T3 for years, including sleeping bags, camping mats, tents, and more.
Stop treating your sleeping bag like a sleeping bag
One of the biggest misconceptions in camping is that you have to zip yourself inside your sleeping bag every night. On the contrary, unless temperatures genuinely demand it, you can simply unzip your sleeping bag and use it like a duvet or quilt.
Modern sleeping bags are designed to compress underneath your body anyway, which means much of the insulation beneath you isn't doing much.
By laying the bag over yourself rather than cocooning inside it, you'll stay much cooler while still having enough warmth if temperatures drop overnight.
If you wake up feeling chilly in the early hours, you can always pull the bag around you without changing your entire setup.
Don't ditch your sleeping mat
When the weather is hot, it's tempting to skip the sleeping mat altogether, especially if you're camping on soft grass. In reality, that's usually a mistake.
A sleeping mat provides insulation from the ground, which can still draw heat away from your body later in the night. More importantly in summer, it also allows air to circulate beneath you more effectively than sleeping directly on the groundsheet.
Inflatable mats are often the better option in warm weather because they create a layer of air between you and the ground and offer much greater comfort than thin foam alternatives.
Swap pyjamas for merino wool
It might sound backwards, but wearing a lightweight merino wool base layer can actually help you stay cooler than sleeping in a cotton T-shirt.
Merino wool naturally regulates body temperature, moves moisture away from your skin and remains comfortable even when you start to sweat. Cotton, on the other hand, absorbs moisture and tends to stay damp, leaving you feeling clammy through the night.
If you're choosing dedicated sleepwear for camping, lightweight merino (125–150 gsm) or a merino/Tencel (merino/nylon) blend is worth considering, especially if you're spending several consecutive nights outdoors.
Icebreaker has a 75 gsm TENCEL option for just £68.
Consider a sleeping bag liner on its own
On particularly warm nights, a silk or lightweight synthetic liner can be all you need.
You can even ditch the tent altogether if you wish
Silk is especially popular because it's soft, breathable and packs down to almost nothing (OEM has an excellent value option), making it ideal for summer camping and bikepacking trips where every gram counts.
It also helps keep your sleeping bag clean, so you won't need to wash it as often.
A lightweight blanket can be enough
If you're camping in the UK during a heatwave, overnight temperatures can remain well above 18°C (as is the case at the time of writing). In conditions like these, even a lightweight camping blanket may be sufficient.
Many outdoor brands, including YETI, which offers the premium Lowlands Blanket, now offer compact insulated blankets that pack down to about the size of a jacket yet provide enough coverage for the cooler hours before dawn.
They also give you far more freedom to regulate your temperature than a zipped-up sleeping bag.
Keep your tent working with you
Finally, remember that your sleep system is only part of the equation.
Open opposing vents to encourage airflow, leave the flysheet off if conditions allow, and avoid pitching where your tent will still be baking in the evening sun.
Even something as simple as choosing a spot beneath partial tree cover can make a noticeable difference to overnight comfort.
A cooler tent combined with a lighter sleep setup is often all that's needed to turn a restless summer night into a genuinely comfortable one.
