Postprandial somnolence

Postprandial somnolence (colloquially known as food coma, after-dinner dip, or "the itis") is a normal state of drowsiness or lassitude following a meal.

[1] While there are numerous theories surrounding this behavior, such as decreased blood flow to the brain, neurohormonal modulation of sleep through digestive coupled signaling, or vagal stimulation, very few have been explicitly tested.

To date, human studies have loosely examined the behavioral characteristics of postprandial sleep, demonstrating potential shifts in EEG spectra and self-reported sleepiness.

[2] To date, the only clear animal models for examining the genetic and neuronal basis for this behavior are the fruit fly, the mouse, and the nematode Caenorhabditis elegans.

[3][4][5] The exact cause of postprandial somnolence is unknown, but there are some scientific hypotheses: Increases in glucose concentration excite and induce vasodilation in ventrolateral preoptic nucleus neurons of the hypothalamus via astrocytic release of adenosine that is blocked by A2A receptor antagonists like caffeine.

[4] Evidence also suggests that the small rise in blood glucose that occurs after a meal is sensed by glucose-inhibited neurons in the lateral hypothalamus.

A common myth holds that turkey is especially high in tryptophan,[24][25][26] resulting in sleepiness after it is consumed, as may occur at the traditional meal of the North American holiday of Thanksgiving.

[medical citation needed] A 2015 study, reported in the journal Ergonomics, showed that, for twenty healthy subjects, exposure to blue-enriched light during the post-lunch dip period significantly reduced the EEG alpha activity, and increased task performance.