I follow along with drinking a glass of water with lemon to activate your digestion system and provide some vitamin C. Some of my healthy snack items are: handful of almonds, pumpkin seeds, small apple, 2 tbs. hummus with 100% whole wheat pita bread (1/2 of slice), banana, 1 tb natural, sugar-free peanut butter on celery sticks or apple slices.
There is this tea known as Yerba Mate. And it has been used in S. America for just such a purpose. I used this tea myself when I had a 3rd shift job. Not only did it keep me from going to the vending machine but it does have some caffeine that also kept me awake without feeling frazzled. As long as you don't add sugar or honey I believe it has a minimal amount of calories - just enough for energy. The loose leaf tea is much tastier than the tea bags and is far more economical.