This stimulation helps her regulate her own physical responses, and also exercises her vestibular system, which controls balance. The sling is in essence a transitional womb for the new baby, who has difficulty controlling her bodily functions and movements. Premature babies who are touched and held gain weight faster and are healthier than babies who are not. Mechanical swings and other holding devices do not provide these same benefits. Babies worn in slings are happier.
Studies have shown that the more babies are held, the less they cry and fuss.
In indigenous cultures where baby-wearing is the norm, babies often cry for only a few minutes a day as opposed to Western babies, who frequently cry for hours each day. Crying is exhausting for both baby and his parents, and may cause long-term damage as the baby's developing brain is continually flooded with stress hormones. Babies who are not wasting their energy on crying are calmly observing and learning about their environment. Baby-wearing is particularly useful for colicky or high needs babies who are far happier being worn, but even the placid, content child will benefit from the warmth and security of being held close. It's hard to find time to exercise when you are a new mother, but if you carry your baby around with you most of the day or go for a brisk walk with your baby in her sling, you will be doing your body good.