My solutions
The long hand
The long hand consists of small plastic balls and has a certain length and weight. The weight is needed to simulate the womb, especially for babies that were born prematurely.
The long hand provides deep pressure to the baby, so that the mother/caregiver can remove her hand after she placed the baby back in their cot. Essentially it will feel as if the mother is still holding the baby.
An infant must be put to sleep while in the drowsy sleep state so that the infant can learn to self-soothe and fall asleep by himself.