How the Pyramids and Stonehenge were build

The Forgotten Technology

does lack of exposure to sunlight contribute to cancer

why do we fall asleep after eating?

Med Hypotheses. 2004;63(5):778-82. Debunking a myth: neurohormonal and vagal modulation of sleep centers, notredistribution of blood flow, may account for postprandial somnolence.Bazar KA, Yun AJ, Lee PY.Department of Dermatology, San Mateo Medical Center, 222 West 39th Avenue, SanMateo, CA 94403, USA. kbazar@sbcglobal.netIt is widely believed that postprandial somnolence is caused by redistributionof blood flow from cerebral to mesenteric vessels after a meal. This beliefpersists despite its apparent contradiction with a well-known neurophysiologicprinciple that cerebral perfusion is preferentially maintained under a widerange of physiologic states. For instance, during exercise when a large amountof perfusion is diverted to muscles, blood flow to the brain is maintained.Furthermore, recent evidence suggests that there is no measurable change ofblood flow in the common carotid artery during postprandial states. We proposean alternative hypothesis that postprandial release of gut-brain hormones andactivation of vagal afferents may play a role in postprandial somnolence throughmodulation of sleep centers such as the hypothalamus. Feeding alters the milieuof hormones such as melatonin and orexins and also promotes central vagalactivation. Emerging evidence suggest that these pathways are also modulators ofneural sleep centers. Potential adaptive explanations of postprandial somnolenceare explored from a Darwinian perspective.