The consensus opinion seems to be that sleep should not have a role in our decision whether or not to stop life support. As smartblkwoman said, "it is very cruel to weigh someone's death by how much sleep you can get." I absolutely agree, and that is why I try my hardest to not let my desire for sleep affect my decision about termination of life support. Most of the time I'm successful. As Dianne said, my hope is that I'm "able to make better decisions knowing that that motivation is there."
But it brings up the more general problem of a physician's personal needs or desires affecting his or her medical decisions. For example, an obstetrician has tickets to a concert in two hours. Does that affect his decision whether to do a caesarean section in a woman who's poking along in labor, versus letting her labor longer? Or a pediatrician wants to be home in time for her son's birthday party, and she has two more patients to see. Does that make her rush through those patients faster than she normally would? A good physician doesn't let his or her personal life affect medical decision making, but we're kidding ourselves if we think there isn't at least a potential problem there.
Commenters also opined that a physician should not be able to unilaterally decide to stop life support and needs to discuss it with the parents. I agree with that, too. My paragraph addressing that issue said "sometimes" I wish we could stop the ventilator on our own. Most of the time I realize that would not be a good thing, that there would be too much potential for abuse by some physicians. Having parents agree is a check and balance in the system. (Sometimes, too, before withdrawing the ventilator I'll ask the nursing staff if they agree with stopping support.) I think, though, that the worry about causing the parents guilt by making them say it's okay to stop the ventilator is a legitimate concern.
These end of life issues are tough. If they're not tough for you, maybe you shouldn't be making them.