Sleep Affects Your Appetite in the Same Way as Marijuana, eLife

Sleep deprivation has long been known to make people crave higher-calorie foods. In a recent study led by Thorsten Kahnt, a neurologist at Northwestern Feinberg School of Medicine, researchers established links between sleep, the endocannabinoid system, smell, and appetite in humans. Their conclusion was stunning: sleep loss influences the same smell-processing neural pathway that smoking marijuana does.
The team asked 25 healthy volunteers to sleep for either 4 hours or 8 hours per night for four weeks, and then switch their sleeping patterns for another 4 weeks. Blood samples were taken from the volunteers. Sleep-deprived volunteers, as expected, had higher levels of 2-oleoylglycerol, a molecule that likely acts on endocannabinoid receptors. However, the sleep-deprived volunteers did not report feeling hungrier than their well-rested fellows, and both groups consumed the same average amount of calories. However, people in the sleep-deprived group consistently chose foods that packed more energy per gram—for example, glazed doughnuts instead of blueberry muffins.
Then the team took MRI scans of the volunteers while they were smelling different kinds of food. The researchers found that sleep-deprived participants’ piriform cortices, which are responsible for interpreting smells, showed increased activity in response to food-related smells, but not in a way that directly correlated with their changes in appetite. When researchers looked at information flow between the insula, a region deep inside the brain that helps regulate food intake, and the piriform cortex, they found that volunteers with higher levels of 2-oleoylglycerol showed consistently less “chatter” between the two regions. A pathway by which the olfactory system and food intake were affected by a lack of sleep was developed by the team and published recently on eLife.
Though the cause-effect relationship between the two regions in the brain is still unclear, the work solidifies the connection between sleep deprivation, sensory processes, and appetite. “It also really underscores the role that the sense of smell has in guiding food choices,” says Kahnt. Kahnt and his team are also going to further investigate the effect of the time of awakening and extended fasting. Poor volunteers.

How do squirrels stay hydrated for months without drinking water, Current Biology

In 1996, archaeologists discovered an ancient battlefield in a narrow, swampy valley that runs along the Tollense River, in Mecklenburg-Vorpommern, 160 kilometers north of Berlin. The site contained metal and wooden weaponry and more than 12,000 pieces of human bone. More recently, new discoveries made in 2016 uncovered a jumble of tools and scrap metal including cylindrical fragments of bronze, along with a bronze knife, awl, and small chisel. While the watery conditions below the surface also preserved bits of wood, divers found more debris from the battle, including arrowheads, dress pins, a bronze knife with a bone handle, and a human rib and cranium. The objects were dated back to about 1300 B.C.E. when bronze was the height of metallurgical—and military—technology.
One surprising finding was the origin of these objects. Dozens of scrap bronze along with small tools for cutting it that were similar to the ones found in Tollense River valley had been discovered in the graves of high-status warriors from much farther south, along the northern foothills of the Alps from eastern France all the way to the modern-day Czech Republic. This suggested that the weapons and bronze manufacturing technology must have traveled hundreds of kilometers away, long before modern communication and logistics systems.
More importantly, it was not only the tools that traveled. Some of the bones found on the battlefield contained a level of strontium that did not match isotopes found in people raised in the region. “This shows people were a lot more mobile than we thought,” says archaeologist Helle Vandkilde of Aarhus University in Denmark, who was not part of the study. “The implication would be the objects accompanied people on the move.”

Video of the week: Watch how humpback whales trap their prey and scoop up fish into their mouths
ISP Sci. Rev. 36 (2019)
Editor: Rossoneri
Integrated Science Program
Northwestern University

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