The sleep system used to be a sleeping bag. Then came quilts that were more or less attached to the pads. And the clothing you bring as an intregral part of your sleep system. But sleeping bags are still a central feature in most gear lists.
As can be seen above a quilt lacks underside. It often has some kind of elastic to keep the edges tucked in around the sleeper, to avoid chilling drafts. The quilt above is homemade, filled with high-quality down. Weight: 600 grams
This quilt is also homemade with synthetic insulation. The outside is ripstop nylon, the inside is more or less see-through mosquito netting, which makes it possible to see the extra layer of insulation for the torso. I use mine mostly in winter for reinforcing my sleeping bag. 640 grams.
A quilt with a hole can be used as a very warm poncho, as well.
For the tundra I want a summer sleeping bag that can handle a frost night. This one is rated at -1 C (30 F) and weighs 685 grams.
For early summer and fall I prefer a warmer sleeping bag. This one is rated at -7 C (20 F). It weighs 885 grams.
Comments and current insights: There are many pros and cons to be taken into consideration when it comes to sleep systems. Quilts or sleeping bags? Down or synthetic? Sometimes one is to prefer, sometimes another. Having used quilts quite a bit, I have returned to sleeping bags, since excellent and light sleeping bags are available on the market. A high-quality sleeping bag costs quite a bit, but for most of us it will last 10-15 years, at least. Lots more on this in the book.