A sleep sack is a wearable blanket that is used in the place of loose blankets in baby’s crib. The sack is worn over pajamas and allows room for movement, but cannot be kicked off during the night. The swaddle attachment keeps baby’s arms close to his or her body in a swaddled position. There is still much that is unknown about the cause of Sudden Infant Death Syndrome (SIDS), but some findings suggest that the rebreathing of carbon dioxide is a possible cause. Loose crib blankets have the potential to become bunched up around baby’s face while sleeping. A sleep sack provides an alternative that keeps baby warm without the potential risks posed by loose bedding.

Also called: blanket sleeper, wearable blanket