He needs a cool, dark, quiet place to sleep during the day. He should go to bed about 10 to 11 hours prior to each shift -- no sleeping right after a night shift. That will give him enough time to get in a short workout and be at work on time and still be safe to drive home the next morning. TiVo his favorite TV shows to watch in the morning. Schedule meals in rotation so that he eats breakfast at home before work (regardless of the time) lunch at work, and dinner after. The typical content of each of those meals provides the fat, carbs, and protein useful for that part of the day. It won't do for him to eat waffles and fruit for dinner (in the am), Turkey sandwiches for breakfast and pork chops with pasta for lunch. That will just fuel him up right before sleep and bog him down in the middle of his shift.
A balanced diet, exercise, and a regular sleep pattern are all necessary. So, don't be tempted to ask him to come to the kids' school during the afternoon when he should be sleeping. It might be day for everyone else, but it has to be night for him without exceptions.
No caffeine starting with the last two hours of each shift.
20 minutes on a treadmill or elliptical machine before work is a great way to warm up the engine.
Be disciplined. It will be tempting to interact with him in lots of ways when he should be asleep. Take him shopping or to the movies or get him to fix the dishwasher, but not when he should be sleeping.
Also, it may be hard for him to get to sleep in the afternoon when he is used to having you there. If you can spare the time, take a little nap in the afternoon when he goes to bed. It will help him sleep, preserve the bond between you, and get you a little rest break too.