53 year old female. I did this while wearing hiking socks in the bathroom floor. I was also brushing my teeth using my electric toothbrush at the same time because that's what I was doing when reading this post.
Eyes closed, I was able to balance on either foot for over a minute, then stopped because 60 seconds was the target if you're 20. Not sure of the absolute longest time since I finished brushing my teeth and counted to over 90 seconds on the last side. I was not having trouble balancing. Maybe strength training and yoga would help?