Big Agnes Cross Mountain 45º Sleeping Bag ($134.95 - $144.95) and Big Agnes Insulated Air Core Sleeping Pad ($79.95 - $129.95), bigagnes.com

The Good: You’ll never fall off your sleeping pad again.

The Bad: All sleep system bags are designed without insulation on the bottom. Choose the wrong pad and you’ll be chilly all night.

The Awesome: You’ll never fall off your sleeping pad again.

The Big Agnes Cross Mountain 45º Sleeping Bag

Staying warm enough is my typical concern when I’m looking for a new sleeping bag, but sleeping outside in muggy, hot Northeast and Mid-Atlantic summer weather can be downright uncomfortable with a bag that’s too insulated. In an effort to find a bag I could be comfortable in while camping at Delaware Seashore State Park in August, for example, I opted for the classic semi-rectangular Cross Mountain 45. The bag is lined with breathable nylon and the shell is constructed with water-resistant ripstop nylon. After pulling the bag in and out of my backpack, stuff sacks, car trunk and more, the shell is holding up well.

Interior fabric loops make it easy to add a bag liner if you’re expecting cooler temperatures and don’t want to buy multiple bags. The Cross Mountain 45 uses the company’s INTEGRITY synthetic insulation, made with 97% recycled content. You can choose whether you’d like a left or right zipper, which I love. The bag also features an integrated full pad sleeve and there’s no insulation on the bottom of the bag at all. Just two thin layers of nylon. Crazy, right?  More on that in “The System” below. Overall, it’s a solid, durable, lightweight (just under two pounds) warm-weather bag.

The Big Agnes Insulated Air Core Sleeping Pad

The Insulated Air Core is one of Big Agnes’s best sellers and it’s easy to see why. The pad utilizes vertical channels running the length of the bag and larger outer chambers to keep you centered on the pad while you sleep. Fully inflated, the Insulated Air Core keeps you a comfortable 3 1/4″ from the ground and PrimaLoft™ synthetic insulation keeps you warmer than a traditional inflatable pad. There are seven sizes to choose from, making it one of the most versatile pads Big Agnes makes. It’s lightweight, low bulk, and packs down to the size of a Nalgene bottle.

I took me approximately 20 full breaths to get the pad inflated and I was comfortable on it all night. The pad’s stuff sack includes a patch kit, which is key if you’re using a Big Agnes Sleep System bag; there’s no insulation on the bottom of the bag to keep you warm and you have to rely on the pad. Though duct tape works for patching holes, it leaves a sticky residue behind. It’s great that Big Agnes anticipates our needs. Overall, it’s a solid addition to my gear closet and I like that the PrimaLoft insulation makes it an ideal three-season pad. I was too warm when temperatures hovered around 70º at night and would consider the less expensive, less insulated Air Core as an alternative for summer camping.

Combining the Two - the Big Agnes Sleep System

Traditionally, sleeping in a tent simply requires setting up your sleeping pad and unrolling your sleeping bag on top of the pad. But if you’re an active sleeper, you might find yourself falling off the pad in the middle of the night, which is both uncomfortable and causes heat loss to the ground. The Big Agnes Sleep System bags are designed to keep you on your pad all night using a thin nylon sleeve that accommodates any 20″ wide pad. All of the sleep system bags have a long opening at the top and a small slit at the bottom. Simply inflate the sleeping pad, slide it into the nylon sleeve at the top of the bag, and use the slits at the bottom to pull the pad through. It took me less than five seconds to figure out how to set the system up. That, the built-in pillow pocket, and the fact that I could comfortably move around in my bag without falling off the pad sold me on the system the first night I used it.

If you decide to invest in your own sleep system, you can use any 20″ wide sleeping pad, or go with one of the Big Agnes models of an appropriate length. I used an Insulated Air Core pad that matched the length of my sleeping pad, but if you’d like extra insulation or padding under your head, Big Agnes makes longer pads that will stick out of the nylon sleeve on regular length bags.

However, it’s important to remember one of the most unique features of the sleep system - there’s no insulation on the underside of the bags. I used the Insulated Air Core for my system because it has a higher R-value than the Air Core and other uninsulated pads. If all you’ve got between you and the ground is a sleeping pad, make sure it’s going to keep you warm enough. Big Agnes pads come with a temperature rating, and by matching the ratings for your pad and bag, you can chose your optimal sleep system.

The Bottom Line? Big Agnes solved one of the biggest problems I have while sleeping outdoors with this system. I stayed on my pad all night and stayed comfortable. It felt like more of a traditional sleeping setup at home with a sheet under me and a comforter over me. I love that you don’t need to use a Big Agnes pad with the system if you have another brand you prefer. I’d definitely recommend this system for summer car camping and backpacking.