I nightweaned my (then) 14mo dd in a desperate attempt to get some rest during the first trimester of this pregnancy. Neither of us left the bed.
Dd was still waking every 2 hours to nurse, as she had since her newborn days. The problem was that I could no longer latch her on and go back to sleep, because the pregnancy hormones caused severe nipple pain. Between the lack of quality sleep and the pregnancy fatigue, I became a monster: angry, depressed, unable to safely drive a car. Nightweaning was truly a last resort for me. I am committed to my nursing relationship with dd and will otherwise allow her to lead the way when it comes to weaning.
That being said, we had quick (though not easy) success with nightweaning. The first night, I talked quietly to dd as she nursed down to sleep about how mama needed to sleep at night and how "nursies" need to sleep at night and told her that we could nurse again when the sun comes up. She woke every two hours, as was her custom. I held her and rocked her, repeated that "nursies are sleeping, we can have nursies when the sun comes up," and sang lullabies as we both cried and she finally settled back to sleep. The second night was much the same. On the third night though, she settled back to sleep without much crying, as I rubbed her back and quietly told her that we could nurse again when the sun comes up and sang to her. Ever since that third night she nurses to sleep, wakes once or twice and I rub her back and sing a lullaby as she settles back down, then she wakes me up as the first morning light comes through the window and we nurse as we both fully wake up for the day.
I would not recommend nightweaning except as a last resort. Please take notice of the bit where I held dd in my arms as she cried herself to sleep-- those were some of the longest, most emotionally painful moments of my life. I am told that some children will completely wean at that point. Bear in mind that there is the possibility that your child will still need you to help them settle back to sleep without the nursing, so you may not be helping yourself get more sleep after all. I am so thankful that dd and I have managed to maintain a strong daytime nursing relationship so far through my pregnancy, in spite of the nightweaning.