My friend and I went camping and she told me that if I slept in a sleeping bag made of polyester, I would be warmer than under blankets and/or with clothes onAfter getting me naked, she zipped me up in oneI do admit it was warm and comfortable but is that THE best way to sleep?
Insulates Against Heat Loss
Warmer than what? Sleeping bags are generally either synthetic fibers or down or a combinationInsulation works by trapping air in and around the material (it is the air that is actually the insulator), just like fiberglass which insulates your homeDown is probably the optimum insulation, but it is more expensive and can get bunched up if not taken care of Synthetic fiber technology (e.g., polyester) has advanced in the past few decades and does a pretty fine job of insulation, the most advanced synthetic insulation actually tries to mimic the properties of downWhen choosing a sleeping bag, look at what the bag is actually rated forThe type of insulation, amount of insulation, and the shape of the bag make a difference in their performanceOn a summer night you don't want a sleeping bag made for arctic conditionsBags that wick perspiration away will also make you feel more comfortableAnd yes, in my experience, one feels more comfortable in sleeping bags with minimal clothing.
