I've tried sleeping bags that zips together. It's OK, or even nice when it's fairly warm. But when it gets cold, my experience is that you lose more heat from not being able to close up at the top particularly well than you gain from the shared space. For warmth it's better to snuggle up in separate bags than to vent like a chimney from a shared bag.


Unless you have some custom arrangement with separate, sealable hoods and a shared body space.