The ClevaMama swaddle to sleep is so snug that it helps to recreate the security and comfort of the womb so your baby can sleep more peacefully and for longer. The snug fit allows enough movement to be comfortable, while helping to prevent startle reflex, one of the main reasons your baby wakes during the night. Swaddling just the upper torso ensures that legs and hips have enough room to move naturally and help prevent hip dysplasia. Adjustable wings grow with your baby. Medical research suggests that babies will sleep better and longer if they are swaddled.