Snacking after dinner often leads to overeating. It just happens that the mindless munchies take over and you end the day by consuming more calories than you burned during the day. If you are dieting you definitely want to avoid that, since your goal is to be in a caloric deficit.
To break the late night snacking habit, I propose that you close your kitchen at 8:00 pm, or whenever you finish your dinner. Yep, just think the kitchen is closed. Don't open the pantry or the cabinet with the crackers, cookies, chips, chocolate - is it just me or do all tempting treats begin with the letter "C"? Keep the refrigerator closed.
The only exception to the Kitchen Closed rule would be to make a nice cup of herbal tea. Chamomile tea can satisfy your sweet tooth and help you wind down at the end of the day. As I write this I am enjoying a cup of decaf Earl Grey with a splash of non-fat milk.