The term "witching hour" refers to the period from midnight to 3am, while "devils hour" refers to the time around 3am. This was exactly right for me last night. Brought to mind the Sarah Connor lines: "The demons come after midnight in the first three hours of the new day when we are alone and vulnerable - deep in sleep and helpless, when we cannot move. They lay on us, press on us, suffocate us. Take from us what is most precious - our lives, our love, our sanity. Our sleep."