If you're the manager, can you sway the owners into relaxing hours? Have you tried?
"Hey guys, I know we are an non-profitable early-stage startup, but do you think we could all try to stick to 8 hour work days?"
I find it interesting that everyone always assumes that working more hours means less quality of life. I thoroughly enjoy my job, so spending more time doing it does not detract from anything.
"Only 13 percent of people worldwide actually like going to work"
http://www.washingtonpost.com/blogs/on-leadership/wp/2013/10...