A tapering mummy-style sleeping bag is easier to travel with since they can be compressed extremely compact. But if you suffer from even a smidgen of claustrophobia, spending a night in one can be like sleeping in a straight jacket.
To make them more comfortable and compatible with those of us who toss and turn, Nemo has created a spoon-shaped sleeping bag which provides extra space where it's needed, without sacrificing portability.
The $230 Rhythm 40 bulges at the knees and elbows to allow the occupant to easily roll over during the night, or strike a more comfortable sleeping pose that doesn't have them just lying on their back. The sleeping bag's also waterproof, for unanticipated leaks and floods in the night, and has a pocket in the hood for stashing a pillow. Suddenly, camping seems a bit less like roughing it.