Sometimes I Spy...

I work in the ER as a nurse, and sometimes when it's slow, I catch myself just watching people come and go... observing them like they're characters in a movie. It's kind of ridiculous because usually there are real lives at stake here, but my mind wanders so much that I've even found myself making up backstories for patients based on their clothes or what little I overhear them saying to their loved ones.... One time, I was staring too long at this old man who kept holding his grandson's hand as the kid cried. The poor thing looked lost and scared, but the grandpa just kept whispering softly in his ear like he had all the answers.... I felt bad afterwards because it's not professional to be so absorbed by someone else's drama, even if they're strangers.... So here's my question: is it okay to take a mental break every now and then... or am I being unfair to the patients and their families? Should I just stick to focusing on what needs to be done instead of people-watching during downtime?