It’s long been believed that a lack of sleep could be bad for the brain. But a new study offers a more colorful, yet dire description of this consequence — it could turn the brain into a “cannibal” of sorts, with synapses being “eaten” by other brain cells, and even increase the chances of chronic sleep loss sufferers acquiring Alzheimer’s disease later in life.
Not getting enough shut-eye at night might not sound as bad as it seems at first, according to a report from New Scientist. Healthy brain connections initially may be protected once brain cells consume their worn-out equivalents. But study lead author Michele Bellesi of the Marche Polytechnic University (Italy) believes that a chronic lack of sleep may have some dangerous long-term effects on the human brain, including a higher risk of neurological disorders such as Alzheimer’s disease.
Together with his fellow researchers, Bellesi came up with this theory after conducting experiments on mice. Multiple groups of mice were compared, with one group being forced to stay awake for eight hours longer than usual, and a second group getting as much sleep as they desired. A third group was forced to stay up for five straight days, in an effort to simulate how a chronic lack of sleep could wreak havoc on the brain.
The researchers focused their attention on glial cells, which, according to New Scientist, serve as the brain’s “housekeeping system.” Specifically, Bellesi’s team was interested in astrocytes, a type of glial cell that removes unneeded synapses to refresh the brain’s wiring, as well as microglial cells, which work by “prowling” the brain for damaged cells and other waste.
Based on the researchers’ observations, astrocytes were active in only six percent of the properly-rested mice’s synapses. But when it came to the mice suffering from a lack of sleep, astrocyte activity was more pronounced, at eight percent of synapses in the group that lost eight hours of sleep, and 13.5 percent of synapses in the group kept up for five straight days.
“We show for the first time that portions of synapses are literally eaten by astrocytes because of sleep loss,” Bellesi explained in a statement.
Previous studies have combined to suggest a wide range of consequences relating to a lack of sleep. An article from WebMD lists some of these negative effects, which include a higher risk of heart disease, loss of sex drive, and in direct relation to the brain’s functions, “dumbing (one) down.” This could mean a person not being able to process what they have learned and gone through during the course of a day, or suffering from a lack of attentiveness, alertness, or concentration, or an inability to solve problems and learn things properly. Other risks may also include forgetfulness, a higher chance of depression, and impaired judgment.
But could a lack of sleep really increase one’s chances of suffering from Alzheimer’s disease or other neurological disorders? Bellesi added that the additional activity of microglial cells in the sleep-deprived mice meshes with existing theories about Alzheimer’s and its risk factors.
“We already know that sustained microglial activation has been observed in Alzheimer’s and other forms of neurodegeneration.”
The Telegraph also noted that chronic sleep deprivation had, in previous studies, been linked to a buildup of brain plaque that causes Alzheimer’s disease and other forms of dementia.
The results of the study, however, do not make any mention of whether getting more sleep could protect the brain’s cells from eating worn synapses, or reverse the damage wrought by sleep deprivation. But New Scientist wrote that Bellesi and his colleagues are hoping to conduct studies determining how long the effects of a lack of sleep could last.
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