Hammocks themselves certainly arent warmer, per se, than a tent, at first glance. It comes down to the insulation underneath you-without some form of insulation, wind steals your heat. There ARE solutions to this; underblankets, proprietary solutions (such as the HH pad), or you can use a regular pad inside it (I have heard mixed results on this, but have no first hand experience yet). Also, its easier to use a quilt, blanket, or open a sleeping bag fully, in a hammock, than it is to squirm into a sleeping bag.