Postprandial somnolence (colloquially known as a food coma, carb coma, or in the African-American community the itis) is a normal state of drowsiness or lassitude following a meal. Postprandial somnolence has two components: a general state of low energy related to activation of the parasympathetic nervous system in response to mass in the gastrointestinal tract, and a specific state of sleepiness. The increased sleepiness is thought to be caused by hormonal and neurochemical changes related to the rate at which glucose enters the bloodstream and its downstream effects on amino acid transport in the central nervous system, though there is a lack of evidence to support this.