Italian scientists have discovered that the brain starts eating itself if the body is suffering from chronic sleep deprivation.
The process is caused by a particular type of brain cells known as astrocytes eating away portions of synapses, the structures that join neurons together. Researchers note that it may not be as dangerous as it sounds, as the synapses that were affected were those older than the rest.
Care for your brain by getting some sleep
Sleep deprivation can be fatal. Previous studies have shown that lab mice can die from sleep deprivation after 11 to 32 days. There are no clear records of someone dying due to chronic sleep deprivation, although researchers agree that sleeping is vital for us to function properly.
Researchers led by Michele Bellesi from the Marche Polytechnic University in Italy found that the brain of mammals is deeply affected by sleep deprivation.
To remain healthy, the brain needs to clean after itself. This process is performed by glial cells, a type of cells that oversee the correct functioning of the nervous system. In this group of cells, we have the microglial cells, which eat away the structures deemed old and useless.
Astrocytes are a type of microglial cell in charge of eating away unnecessary neuron connections, formally known as synapses. The process occurs regularly during sleep, but now researchers saw that it might also occur during sleep deprivation.
For the study, researchers took several groups of mice and exposed them to different sleep deprivation scenarios. One group was allowed to rest between 6 and 8 hours, another was woken up during sleep, a third group was not allowed to sleep for 8 hours, and the last group was forced to remain awake for five days in a row.
The team focused on how astrocytes performed in each cluster. As the mice rested less, their astrocytes were more active, getting to the point of eating synapses that would not be consumed in normal conditions.
Rested mice had active astrocytes in 5.7 percent of their synapses, while chronically sleep-deprived mice had active astrocytes in 13.5 percent of their synapses.
The astrocytes would consume the largest and most used synapses. Researchers compared to the process as if the astrocytes were getting rid of old furniture.
Astrocytes eating away synapses occurred only during acute and chronic sleep loss, but not in the cases where the mice were rested and when they were woken up during sleep.
No other practice has been associated with an increased astrocytic activity, which is a concern because Alzheimer’s disease is known to be associated with increased microglial activity.
Alzheimer death rates in the U.S. are at 55 percent, according to the CDC. It is the most common cause of dementia, although it usually affects people older than 65. Over 5 million Americans suffer from the disease, and by 2050 the number of patients is expected to rise to 16 million.
Some suggest that the increase in mortality is due to older populations getting bigger, paired with a higher rate of early diagnoses.