Closed-cell foam sleeping pads offer the most insulating value for their weight and are the least expensive choice. The drawback is that they don't roll up very compactly and are too thin to provide much cushioning. They're favored by young, somewhat stoic hikers, and they're so inexpensive and useful that it's a good idea to try one before spending more money for a self-inflating sleeping pad. If you find you don't sleep well on a closed-cell camping mat, or you wake up with aching or numb hips or shoulders, then you can always use the pad later for extra insulation when camping in winter. You can easily cut up a camping mat to make warm seat cushions, too.
Reviews recommend against buying a cheap closed-cell sleeping pad from a discount or "big box" retailer, saying these mats tend to get brittle in cold weather, absorb water and don't last as long as sleeping pads from major brands. Instead, reviews recommend two closed-cell sleeping pads by Therm-a-Rest. None of these closed-cell pads are as comfortable as a self-inflating sleeping pad, but they make good insulators underneath for extra-cold nights.
The 3.7-ounce Gossamer Gear NightLight Torso (*Est. $18) has an R-value of 2.27, higher than that of its popular rival, the Therm-a-Rest Z-Lite (*Est. $35). BackpackingLight.com recommends the NightLight Torso for three-season hikes. It's only 18 inches wide instead of 20, and the 29-inch length is designed to cushion from shoulders through hips. Like the Z-Lite, it uses closed-cell foam in an egg-crate design and folds neatly for packing. It makes a good frame for ultralight backpacks, and is also useful for adding extra torso cushioning to other sleeping pads with minimal added weight. For hikers taller than 6'2", BackpackingLight.com recommends the larger 7.5-ounce Gossamer Gear NightLight 3/4 sleeping pad (*est. $32).
The Therm-a-Rest Z-Lite (*Est. $35) is slightly thicker at 0.75 inches, but has a lower 2.0 R-value. The foam is shaped in an egg-crate design instead of ridges, and the Z-Lite folds accordion-style instead of rolling up for travel. It's one of the top-rated sleeping pads at REI.com, though several self-inflating sleeping pads rank even higher there. In the regular length it weighs 15 ounces, but the 47-inch Z-Lite Short (*Est. $30) is four ounces lighter.
The Therm-a-Rest RidgeRest (*Est. $35) is named for the ridges that give it a non-slip texture. It's 5/8-inch thick, weighs 14 ounces in the regular 72-inch length and has an R-value of 2.6. BackpackingLight.com recommends layering two of these sleeping mats for winter camping for a total R-value of 5.2. The RidgeRest also makes a nicely padded frame inside a backpack, as its 20-inch width fits most packs. The 42-inch-long version (*est. $20) weighs just nine ounces and is suitable for three-season hikes.
Reviewers say that the Gossamer Gear sleeping pads are lighter, warmer, more resilient and even more durable than the Therm-a-Rest Z-Lite. This makes the NightLight Torso a good choice for an ultralight sleeping pad for three-season use. The full-length Z-Lite and RidgeRest pads are better for winter, though.