To sleep or not to sleep...
The ground is cold, so I need a big, full length pad The best insulation from the cold ground is also the lightest...a closed cell foam pad. And by cutting the pad to just the length of your torso, it is even lighter. Lay down on the ground to find out which parts of you are actually touching the ground...from the bottom of your torso down, probably not much depending on how you sleep. I'm a back sleeper, so it's mostly just the heals of my feet. I insulate them by putting my Tilley hat inside the foot box of my quilt, under my feet. You could also use your backpack as insulation under your legs and feet, which makes it a dual use item. Oh yes, a multi-use item...the UltraLight backpackers quest! The key is to keep your torso and feet insulated from the cold ground. I'm 6'2" tall, and am very comfortable down to around freezing on a 3/8" x19 1/2" x 41" closed cell foam pad that weighs only 3.8oz. For warmer conditions, I use a 3.0oz 1/4" thick pad.
I'm uncomfortable laying on the ground so I need an inflatable mattress I have used everything from a 2_1/2" thick inflatable mattress to a 1/4" thick foam pad, and for me it makes very little difference in how well I sleep. Foam pads do a great job of softening the sharp edged objects such as rocks and sticks so they are not poking you. If your back gets sore like mine does from lying on the ground, try this...take your rain jacket, fold in half lengthwise, then roll it up into a the shape of a cylinder. Now place it under your sleeping pad right in the small of your back. Ahh... instant relief! No inflatable mattress I have used works as well.
I can't sleep without my camp pillow I also like to sleep with a pillow, but I can always find a way to make my head comfortable without carrying an extra piece of gear. Typically it's my spare clothing and insulated jacket inside a stuff sack. If it's so cold that I'm wearing everything I packed to stay warm while sleeping, I will just roll my backpack up and slide it into the stuff sack. You would be amazed at how comfortable this is, and it doesn't add any pack weight.
Other techniques Some people swear by night time pain relievers (Tylenol PM, Nyquil, etc), but for me, they only work for a couple of hours or so, then I'm wide awake again. Others say that if you're tired enough you will eventually sleep. While this is true, it makes for a rough first night or two, and the vast majority of people go backpacking for only a few nights at a time. Making yourself comfortable is the key. By insulating myself from the cold ground and supporting my lower back, I can sleep well on the ground in UltraLight style.