Postprandial somnolence

Source: Wikipedia, the free encyclopedia.

Frederick Arthur Bridgman – The Siesta (1878)
An oil painting of a young woman having a siesta, or an afternoon nap, which usually occurs after the mid-day meal.

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

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.[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]

Physiology

The exact cause of postprandial somnolence is unknown but there are some scientific hypotheses:

Adenosine and hypocretin/orexin hypothesis

Increases in glucose concentration excite and induce vasodilation in

glutamatergic arousal pathways of the brain, thus decreasing the activity of those pathways.[7]

Parasympathetic activation

In response to the arrival of food in the stomach and small intestine, the activity of the parasympathetic nervous system increases and the activity of the sympathetic nervous system decreases.[8][9] This shift in the balance of autonomic tone towards the parasympathetic system results in a subjective state of low energy and a desire to be at rest, the opposite of the fight-or-flight state induced by high sympathetic tone. The larger the meal, the greater the shift in autonomic tone towards the parasympathetic system, regardless of the composition of the meal.[citation needed]

Insulin, large neutral amino acids, and tryptophan

When foods with a high

large neutral amino acid transporter at the blood–brain barrier.[13][12] Uptake of tryptophan by the brain thus increases. In the brain, tryptophan is converted to serotonin,[14] which is then converted to melatonin. Increased brain serotonin and melatonin levels result in sleepiness.[15][16]

Insulin-induced hypokalemia

Insulin can also cause postprandial somnolence via another mechanism. Insulin increases the activity of Na/K ATPase, causing increased movement of potassium into cells from the extracellular fluid.[17] The large movement of potassium from the extracellular fluid can lead to a mild hypokalemic state. The effects of hypokalemia can include fatigue, muscle weakness, or paralysis.[18] The severity of the hypokalemic state can be evaluated using Fuller's Criteria.[19] Stage 1 is characterized by no symptoms but mild hypokalemia. Stage 2 is characterized with symptoms and mild hypokalemia. Stage 3 is characterized by only moderate to severe hypokalemia.

Cytokines

Cytokines are somnogenic and are likely key mediators of sleep responses to infection[20] and food.[21] Some proinflammatory cytokines correlate with daytime sleepiness.[22]

Myths about the causes of post-prandial somnolence

Cerebral blood flow and oxygen delivery

Although the passage of food into the gastrointestinal tract results in increased blood flow to the stomach and intestines, this is achieved by diversion of blood primarily from skeletal muscle tissue and by increasing the volume of blood pumped forward by the heart each minute.[citation needed] The flow of oxygen and blood to the brain is extremely tightly regulated by the circulatory system[23] and does not drop after a meal.

Turkey and tryptophan

A common

chicken, beef, and other meats,[27] and does not result in higher blood tryptophan levels than other common foods. Certain foods, such as soybeans, sesame and sunflower seeds, and certain cheeses, are also high in tryptophan. Whether it is possible or not that these may induce sleepiness if consumed in sufficient quantities has yet to be studied.[medical citation needed
]

Counteraction

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.[28]

See also

References

  1. ^ Drayer, Lisa. "Are 'food comas' real or a figment of your digestion?". CNN. Retrieved 11 July 2019.
  2. S2CID 26531287
    .
  3. PMID 27873574
    .
  4. ^
    S2CID 3628811
    .
  5. PMID 28193866
    .
  6. S2CID 15036932
    .
  7. PMID 25131833
    .
  8. ^ "The Autonomic Nervous System". Archived from the original on 11 June 2008. Retrieved 12 June 2008.
  9. ^ Streeten, DVH. "The Parasympathetic Nervous System". National Dysautonomia Research Foundation. Retrieved 18 July 2010.
  10. PMID 6259925
    .
  11. PMID 12499331
    .
  12. ^
    PMID 22820012
    .
  13. PMID 10518579
    .
  14. S2CID 14345137
    .
  15. PMID 17284739
    .
  16. ^ "The Glycemic Index Concept | Official web site of the Montignac Method". www.montignac.com. Retrieved 17 March 2018.
  17. ^ "Sodium Pumps". Vivo.colostate.edu. 29 April 2006. Archived from the original on 29 July 2012. Retrieved 6 February 2013.
  18. ^ "Hypokalemia - PubMed Health". Ncbi.nlm.nih.gov. Retrieved 6 February 2013.
  19. PMID 21686739
    . Retrieved 6 February 2013.
  20. doi:10.1615/CritRevImmunol.v37.i2-6.70
    .
  21. PMID 29705519
    .
  22. doi:10.1093/sleepj/zsx050.784
    .
  23. ^ "Anesthetist: Vascular Autoregulation". Anaesthetist.com. Retrieved 12 June 2008.
  24. ^ Helmenstine, Anne Marie. "Does Eating Turkey Make You Sleepy?". About.com. Archived from the original on 7 August 2011. Retrieved 13 November 2013.
  25. ^ "Is there something in turkey that makes you sleepy?". HowStuffWorks. 7 November 2007. Retrieved 13 November 2013.
  26. ^ McCue, Kevin. "Thanksgiving, Turkey, and Tryptophan". Chemistry.org. Archived from the original on 4 April 2007. Retrieved 17 August 2007.
  27. ^ Holden, Joanne. "USDA National Nutrient Database for Standard Reference, Release 20". Nutrient Data Laboratory, Agricultural Research Service, United States Department of Agriculture. Retrieved 2 October 2007.
  28. S2CID 5388522
    .
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