Pork is a common source of protein in the United States. It is frequently used in breakfast items such as omelets, quiches and breakfast sandwiches and is also served in main entrees, stews and side dishes. Pork sausage is commonly used in Tex-Mex style chili and is used as a breakfast side dish in link and patty form. Although pork is a rich source of protein, it can also cause feelings of fatigue and sleepiness.
Pork contains tryptophan, an amino acid that your body uses to manufacture niacin and serotonin. A 4-oz. serving of ground pork contains 0.242 g of tryptophan, and a 3-oz. pork chop contains about 0.33 g of this amino acid, according to the U.S. Department of Agriculture National Nutrient Database. Serotonin is a neurotransmitter chemical that has a calming effect on the brain and central nervous system. An elevation in serotonin level may trigger feelings of sleepiness.
Pork requires more extensive digestion than other sources of protein such as legumes, seeds, nuts and soy products. The digestion process requires an elevated concentration of blood to your digestive system, which pulls blood away from your organs and muscle tissues, according to certified nutritional consultant Phyllis Balch, author of "Prescription for Nutritional Healing." This can lower the availability of nutrients and oxygen to your brain and other organs, which can produce fatigue and sleepiness.
Red meats such as pork are high in saturated fats -- a 4-oz. serving of ground pork contains about 8.893 g of saturated fats, and a 3-oz. pork chop contains about 2.448 g, according to the USDA National Nutrient Database. Saturated fats can contribute to fatty blockages in your arteries and blood vessels, according to Balch. Fatty blockages can restrict blood flow through your circulatory system, which can deprive your organs and muscle tissues of oxygen and nutrients, causing fatigue and sleepiness.
Obtain lean protein from sources such as lentils, chickpeas, soy products, seeds and nuts instead of pork. Tofu contains a similar amount of tryptophan -- about 0.31 g per 1/2 cup serving -- but is lower in saturated fats than pork. Nuts, seeds and legumes do not contain significant amounts of tryptophan, and the fats in these foods are primarily unsaturated fats, which may help reduce fatty deposits in your circulatory system, according to Balch. These foods also contain dietary fiber, which aids in proper digestion, reducing sleepiness and fatigue after eating.