Sleep is a function of the brain: Comment on “Norepinephrine is the primary promoter of fluid clearing” by Nedergaard and Zee

There is other evidence that sleep’s function goes beyond the central nervous system. The release of certain hormones is promoted by sleep. This process has various physiological effects, including lowering the risk of cardiovascular disease and some cancers. Inadequate sleep can slow production of beneficial hormones, including cortisol and growth hormone. melatonin has been shown to suppress breast cancer cells’ ability to survive, spread and develop resistance to drugs.

People who listened to pink noise had less morning cortisol levels, which is associated with higher heart rate, and improved parasympathetic activity, which is associated with lower blood pressure. During sleep, parasympathetic activity gives the cardiovascular system a much-needed break. “We know that if you don’t sleep well, your heart rate and blood pressure go up and you are at greater risk for cardiovascular disease,” Zee says.

Sleep is seen as a function of the central nervous system. But that can’t be entirely the case, because creatures without central nervous systems also show sleep-like behaviour.

Franks disputes this characterization and maintains that his results directly contradict Nedergaard’s. He says that his data cannot be reconciled with her conclusions about clearing during sleep, because he showed that the brain was retained at higher concentrations during sleep.

Nedergaard says that sleep is the period where our brain doesn’t just rest, but it does all the housekeeping. “The glial cells are the cleaning crew that come in when the brain is quiet and do the things that other organs do when we are awake. It’s a function of the brain that’s not compatible with wakefulness

After this finding, Nedergaard and her colleagues began searching for the fluid clearance drivers. The heart is one way, but Nedergaard says it’s more likely to account for movement of fluid than its clearance. In February 9, she and her colleagues said that norepinephrine is the primary promoter of clearance through constriction and dilation of arteries. And regular oscillations of norepinephrine levels in the brain occur during deep, slow-wave sleep.

Sleep is thought to not only help memories to take root, but also clear the brain of anything superfluous. Maiken Nedergaard is a neurological scientist at the University of Rochester in New York.

The authors asked them to remember the words during the day, and then they slept. Overall, Zee says, those that had pink-noise stimulation performed almost 30% better on memory tests than did those who listened to the control sounds.

Source: Sleep is essential — researchers are trying to work out why

The Effects of Sleep Deprivation on Genes Induced by the Cellular Receptors at the Absorption of Fat in Animals

The purpose of sleep has always been to maintain brain health. There is so much brain development happening at those stages that babies and teenagers sleep for such long periods of time.

Most genes in rats seem to be active when the animals are awake. Genes that are upregulated during periods of sleep deprivation are responsible for functions such as energy metabolism, hormone reception and protein synthesis5. In a 2023 study, researchers in Brazil found that fruit flies that were sleep deprived showed overexpression mostly of genes that affected metabolism, glucose, triglyceride and levels of the hormone dopamine6.

The same thing happened in animals. When the animals were sleep deprived, they stopped expressing genes for fat absorption, because they were allowed to sleep for small periods. Organelles called mitochondria sense this nutrient deficiency and signal cellular enzymes to make ROS to stimulate the proliferation of cells in the gut that are better at absorption, Rogulja says. After a day or two of sleeping in mice, he could see some fat in the animals’ abdominal area. They had no nutrition but their guts were full of fat after five days.

Source: Sleep is essential — researchers are trying to work out why

Why Sleep is Essential — Researchers are trying to find a solution to the human brains’ problems in the early stages of Alzheimer’s disease

“We looked at tissues all over the body,” Vaccaro says. “We looked at the brain and didn’t see anything. Thegut showed the most damage when flies began to die.

After determining the ten-day timeline for sleep deprivation and death in flies, Vaccaro, who had previously studied sleep deprivation and ageing, began looking for markers of ageing in these insects. She and her colleagues found that the concentrations of ROSs in the guts of flies were at their highest when the animals were dying. Small amounts of ROS are beneficial — they regulate the body’s immune response and help cells to defend against pathogens. These molecule accumulate to toxic levels without sleep.

Likewise, when the brain is further from its critical point, a person will feel more tired and need to fall asleep to reset. The closer the brain is to its critical point the more likely the person is to stay awake, because they will have plenty of capacity for doing and learning.

The workings of a home heating system are similar to that of Hengen. A drop in a room’s temperature below the set point causes the heater to turn on, restoring the environment to the desired level of warmth.

He said it was a light bulb for him. If you persist in letting machine learning learn, the wheels will come off and the thing will stop. It fails.

Source: Sleep is essential — researchers are trying to work out why

Night-shift workers are more likely to have depression, anxiety and self-harm than those in the brightest quartile for daytime light exposure

What’s the most important function of the brain? It might be good to say a specific task, such as communicating, finding food or avoiding predator. It is not possible if the brain’s cellular machinery isn’t functioning reliably. Indeed, it is maintaining that reliability that might well be the main purpose of sleep, says Keith Hengen, a neuroscientist at Washington University in St. Louis, Missouri.

When sleep-deprived animals die, it seems like the same thing every time. They began dying within ten days after they lost most of their sleep. The implications of those studies for other animals, including humans, was intriguing.

She expected the questions would take a long time to answer. But in six months, Rogulja’s postdoctoral assistant, Alexandra Vaccaro, found a tantalizing clue.

These data revealed that those who were in the top 25% of the group for the brightest night-time light exposure had 30% higher odds of major depressive disorder, 27% higher odds of self-harm, 21% higher odds of psychosis and 23% higher odds of generalized anxiety disorder than did those in the bottom 25%. By contrast, those in the top quartile for daytime light exposure had 19% lower odds of major depressive disorder, 24% lower odds of self-harm and 31% lower odds of psychosis than those in the lowest quartile of daytime light exposure. The associations persisted even after exclusion of night-shift workers from the analysis.

The influence of early lectures on the risk of cardiovascular disease and death in first-time parents of babies with pre-existing postpartum insomnia

Babies are bad for sleep because they are pre-existing insomnia. In an effort to help first-time parents who are struggling with these dual sleep challenges, researchers in Australia and Israel trialled two interventions aimed at reducing postpartum insomnia in 127 individuals who were due to give birth to their first child.

The team found a correlation between the duration and amount of daytime naps that someone took and their risk of cardiovascular disease and death. This link was especially apparent in people under the age of 65, and in women aged 65–74. Women of this age who napped more than five times in a week, or for longer than 50 minutes at a time, had significantly higher risk of death from heart disease compared with those who napped less frequently and for shorter times. No such association was seen in individuals aged 75 or older.

Researchers used Wi-Fi connection logs for about 23,000 students to reveal that attendance at lectures starting at 8 a.m. was 10 percentage points lower than at those with later start times. The researchers studied the sleep habits of students who wore wrist devices to monitor their activities, as well as those who did not attend early classes, which resulted in lost one hour of sleep. The academic toll of early lectures has been shown by the grades of about 34,000 students, which show a significantly lower average for students on courses with three to five early lectures per week.

Around one in five adults in the United States use alcohol to help them get to sleep. Brown University and the E.P. Bradley Hospital found that drinking before a night of sleep doesn’t affect REM sleep as much as one might think.

30 healthy adults aged 22 to 57 were given a drink that was either a mixer or a mixer and alcohol, which was designed to bring their blood alcohol level to 0.08 milligrams per liter for the average man, just one hour before lights out. The participants had their brain activity recorded by the polysomnography machines. The groups were swapped over to the other drink type for the final three nights.

The results raise the prospect that the age-old practice of rocking someone to sleep could have clinical benefits in individuals with diseases that reduce sleep quality.

Another group of flies that had been genetically engineered to develop Alzheimer’s disease, which is known to interfere with healthy sleep, were placed in the vibrating tubes for longer stretches of time to see what effect the induced sleep had on disease markers. The researchers found that these flies not only slept better than those who were not vibrated to sleep, but that they also had less accumulation of mutant amyloid-β and tau proteins in the brain, which are hallmarks of the disease.