I believe that.
>Is that particularly realistic?
The only issue is that at 5am, there won't be daylight during the winter. Lack of daylight presents safety issues and makes it more difficult to wake up.
My freshman year of high school my school was under construction so I was bussed across town. Which meant I had to wake up close to 5am. I don't remember staying up especially late, but I was perpetually tired. Id sleep on the bus both ways.
In college I had a semester when I had a 5am class. I found it much easier to stay up all night and crash after than to wake up for class.
Perhaps 5am is just a difficult time to wake up.
To be clear, this wasn't just my seminary class- this is the way teens in the seminary program have handled it for years and years, so it may not be the biggest but it's definitely not the smallest sample size available.
Again, YMMV. I openly admit that I'm biased in my thinking because of the anecdata.