Who's up for a hike?

Camping is great. I do it as often as I possibly can. I've camped in rainforests, in the bush, and on beaches. I've camped in sauna-like heat and bone-chilling cold. I've camped for a weekend, and I've camped for months at a time.

The one thing that I've never been able to understand about camping though, as related to the human proclivity to solve problems, is why we still are not able to take a hike (an action that goes hand in hand with camping) in the middle of the night while staying comfortably warm like you would be in your toasty, cold-weather sleeping bag.

How has someone not though about this? It has practically invented itself...