Apparently, Xubuntu is totally unable to wake up. So when it goes to sleep, for whatever reason, you lose all usaved work. No Ctrl+Alt+F1, nothing. It is there, the machine is on, but the only thing you can do is a hard shut down.
But it still goes to sleep/death after 45 minutes, the default setting.
What can I do to just turn off all sleep functions?
I'm using Xubuntu 16.04 on a Intel NUC. Before that I was using plain Ubuntu on this same machine (but it took too much RAM) and it could wake up without any problem.