Do you mean for the biofeedback? If I recall, my sessions were only 30 minutes each time. It was not stressful at all. There’s no pain, no shocks, nothing invasive. It was little wires taped to my head.
If you read @johnbishop post again, he added a link with the different types of biofeedback. https://connect.mayoclinic.org/comment/685681/

The time went so quickly because I was very focused. Since I was there for anxiety treatments I found it all very relaxing and a means to find relief. It’s not like you’re a character out of some science fiction movie with electrodes and probes. 🙃
I hope you don’t mind my asking, but what are the triggers for your anxiety?