10 year vampire here. When I have to swap, I'll just condense my misery into one day. Curl up with a good book, some netflix, or something and stay up until you would go to bed on your new schedule. Like if you have to get up at 6pm, stay up til about 10 am a day or so before. If you are going to be night shift for any length of time, get blackout curtains for your bedroom.