This is something that has been talked about before, but this story is a great example of when put to work, the pets are helping humans to heal.
While I faced a life threatening issue, my cat Cleo would come in every day and lay next to me or on my chest. She kept me calm and relaxed as my mind was going through a lot of stress. Likewise my dog Buster would come in and rub his head on my hand in what I thought was an attempt at showing affection.
There have been many times while our family has gone through stress, anxiety and or even random general sickness that our pets have reached out to show calm affection.