Applying deep pressure to the body can induce a great sense of tranquillity.
Farmers discovered this a long time ago (using squeeze chutes), which inspired Temple Grandin to invent a ‘hug machine’ for herself, so she could apply deep pressure to her body to calm her down.

Deep pressure is absolutely amazing, and for people with autism, it feels like being hugged for the first time – in a lifetime. The calming effect of a hug, which you can not achieve by hugging, can be achieved by deep pressure. Once you feel this, you finally understand why people like hugs. 🙂
After Mrs. Grandins invention of the hug machine, several commercial products have come available to apply deep pressure. The most well known are the Squease Vest and weighted blankets.