How long have you been smoking meats and how experienced are you with your smoker, fuel types, etc? It makes a huge difference and if this is your first brisket, cliffcarter has your answer - do it during the day. I would add, monitor you temps regularly (when I started I checked them every fifteen minutes, less as I got more experience). and hopefully you have or are keeping going to keep a log so you can work out the quirks of your equipment and fuel types. You will most likely have to add more of whatever you are using for your smoke flavor (Apple, mesquite or whatever) for at least the first three hours unless you are using enough chunks to last that long. The size/weight of your brisket also makes a difference. Then there is your heat source - I have used a mix of good old Kingston regular, competition and lump in various proportions to get the temp up and steady for reasonably long periods, but still have to add every so often and what I add depends on whether I need to extend or raise the temp, etc. A wireless temp (meat and grill temp) system can be valuable if you want to have them wake you up when they change and the smoker needs tending:-)
Bottom line - it is not a throw it in the smoker, go to bed, wake yup and it is done process. Good luck!
Pete
