Whoa,
My work days are usually 10 hours a day 6 days a week. Some weekends I work all one day, others I spread it out across both days (like this weekend). I'm doing Developmental Psych with a focus on research, but even my wife who finished a 2 year masters program in 1 year for Microbiology, Immunology, and Molecular Genetics didn't have it that bad. The PhD students who I met in engineering, physics, social sciences, humanities.. none of them have it that bad. But, it also depends on your advisor. The thing is, many of the students in the "hard" sciences don't ever have to worry about working outside of their research because of how well those areas are funded. Whereas I have to work another job along side my program and it's requirements.
Then again the average number years of completion for my program is 6 years.. you can technically do it in 4 years (I know one person who has done this), and I can see how my life would be more like your wife's life if I tried to do it in 4. I Still have to schedule in the free time though or pay for it later.
I would say that I do get xmas off, but should work through it.. I do pay for it later but oh well. My summers are pretty laid back, even if I'm working the same wours it just feels different because of the longer days.
Anyways, I'm finishing up my last class this quarter, so I'm pretty happy about that, now I can just focus on research