It's perfectly normal to feel a bit sluggish after lunch, but when you're working, at school or managing the household, you simply don't have time for an afternoon nap. Certain foods, particularly simple carbohydrates and proteins that contain tryptophan -- and worse, a combination of the two -- are most likely to trigger this tired feeling. Fortunately, by eating the right combination of foods, you can wake up and get your work done.

In some cases, it's not necessarily the foods that you eat during lunch that make you tired, but the lack of foods before lunch that are the cause. Eating a small, healthy breakfast will get your day off to an energetic start. Choose oatmeal, whole grain toast, fresh fruit or a smoothie. If a long time elapses between the time you eat breakfast and the time you eat lunch, consider a small mid-morning snack. The benefit of these meals is that you're not starving when it's time for lunch, so you won't be tempted to eat too much, which can lead to sluggishness.

Eating a heavy meal, such as a pasta with cream sauce or a meatball sub, can make you feel tired after lunch. Instead, opt for something a bit lighter. For example, enjoy a large salad with light dressing and a protein such as chicken or tofu. Or eat a tuna sandwich with a side of fruit. A healthy lunch for school-age children should be between 600 to 800 calories. Adults may need less, especially if they're trying to lose weight.

A combination of whole grains and protein can help keep you going. When you eat simple carbohydrates, such as white bread or a candy bar, you get an initial rush of energy, but then your energy levels crash. Complex carbohydrates, such as whole grain products, release energy more slowly. If you're craving pasta, choose a whole wheat pasta with ground meat and a marinara sauce. Other alternatives include brown rice and chicken or a sandwich on whole wheat bread.

Foods that contain fiber help keep you full, but they also slow down the release of carbohydrates, which can help you feel more energized. Fresh fruits and vegetables tend to be particularly high in fiber, so they make an excellent side dish with your meal. Whole grains and beans also contain fiber, so a bean burrito with a whole grain tortilla is a smart choice.

If you're not properly hydrated, you're more likely to get sleepy, so choose to drink water with your meal rather than sodas or other sugary drinks. In addition, a watery fruit, such as watermelon or cantaloupe, can increase your hydration.