Hi Alan,
I am using NxStage and Nocturnal as well. You right it does make the loud noise during the balance check every 30 minutes, but you can change that to do it every 60 minutes and that helps. Beleave me, after a while you will get use to the noise and it does not wake me up anymore. It took me about 2-3 weeks, but I sleep like a baby now.
To change it from 30 to 60 minutes, you need to go into system settings. That can be done when you are not using the machine. Turn the machine on and press your green treatment button as soon as you hear the first beep. The system number you are looking for is 43 and you will see that it is set for 30. You can change that to anytime from 15 to 60 minutes.
Something else you can do is to dim the lights by changing system setting 37. All this is in your manual, but feel free to ask any question here at IHD. We have a form just for NxStage users at
http://ihatedialysis.com/forum/index.php?board=37.0Welcome to the club!