Thanks for everyone's posts on this forum; I've never posted before, but found the site very useful.
I've always been a cold sleeper, but I recently bought a new sleeping bag and down jacket to remedy the situation. I got a WM Alpinlite bag and a Montbell UL Alpine Down Parka. I tested them last night for the first time, thinking my problems would be solved, at least at moderate temperatures. I was still cold.
Details: I was camped at the Highland Mary Lakes in the Weminuche Wilderness in Colorado. It was around 12,000 feet, but I think the temperature was around 40 last night, although that's a blind guess. It was certainly above freezing, and there was little wind. There was some frost on the tent in the morning, but no liquids in the tent froze. I was in my tent (a Black Diamond Skylight) and using a no-name closed-cell foam pad from REI. I was wearing a couple light baselayer shirts, thick socks, a pair of shorts (didn't have dry pants) and fleece balaclava, in addition to the down jacket. I was cold enough to stay awake. I was surprised by this, because I didn’t think it was a very cold night and I wasn’t particularly cold when I was cooking, etc.
My own impression was that the bag is too wide for me. I had been using a ratty old REI Sub-Kilo that was around 59' wide, so the 64' Alpinlite felt like too much space to fill. I'm 5'10, 140 lbs, pretty skinny. (I knew I didn't need a wide bag--I bought the Alpinlite because it was on sale for a hefty discount. I didn’t truly realize how wide it was until last night.) I spent a lot of the night trying to stuff the empty spaces of the bag under me to make it snug on top. Would having a too-wide bag make me that cold? I know my pad wasn’t the warmest—I own a Big Agnes air core, just didn’t want the extra weight yesterday—but shouldn’t I have been warm enough anyway, at least 10-20 degrees above the temperature rating? What is a “normal” width for a regular size bag?
Right now I’m thinking I’m going to sell the bag and buy something warmer and narrower. I love the quality of the Western Mountaineering bags, so I’m thinking of buying a Versalite, but its only a couple inches narrower and 10 degrees warmer. Opinions?