Mummy Sleeping Bags

Mummy bags have less space in the foot section than rectangular bags. This means less space that the sleeper needs to warm up, so – generally – a mummy bag is warmer than a rectangular bag of the same weight. However – the actual shape and construction of a mummy sleeping bag affect how warm it is; not all mummy bags insulate equally well.

Generally, a ‘tapered rectangular’ bag has more room for the sleeper to move than a mummy bag - a tapered bag may be more comfort-oriented. However – mummy bag shapes vary significantly; some are very narrow. Sea to Summit mummy bags have enough room for the sleeper to move without compressing insulation at the knees and hips.

Mummy sleeping bag shapes vary significantly; some are very narrow, and do not work well for side-sleepers/stomach sleepers. Sea to Summit mummy bags – particularly the Comfort and Versatility models like the Ascent - have enough room for the sleeper to sleep comfortably in any position. 

Not all mummy bags can be zipped together. Sea to Summit bags designed to ‘couple’ have side zippers that are the same length, so those unisex bags can be zipped to Women’s-specific bags regardless of the length of the bag. Read which bags can be zipped together here. 

A synthetic-insulated mummy bag should always be stuffed; rolling the bag means the direction of compression is always the same. This negatively affects the insulation in the footbox (at the center of the of the roll) most. Down bags can be stuffed or rolled; stuffing is usually better.