Over many decades, researchers have been struggling to build a firm connection between sleep, mind, and body. Thanks to modern research, it has now become possible to solve many mysteries concerning the role of sleep in regulating physiological aspects of our body.
Apart from replenishing energy, sleep cleans-up waste products from brain, helps forming memory, regulates emotions, learning, and many more. In simple words, a good night sleep is an essential part of our life.
LOSING SLEEP INITIATES BRAIN LOSS IN THE LONG RUN
A new research conducted by neuroscientist Michele Bellesi from the Marche Polytechnic University, Italy, has surprisingly shown that similar to well-rested brain, poor sleep habit also starts clearing brain debris with an exception that it predisposes brain to a hyper-activated state.
Although sounds beneficial, it may lead to potential brain loss in long runs, as in Alzheimer’s disease, by potentially removing essential brain components.
BRAIN’S CLEANING MACHINERY
Microglial cells mainly participate in clearing out old and overused cells through a process called phagocytosis – a process of eliminating cell debris by engulfing them. Likewise, astrocytes trim unwanted brain connections, called synapses, to keep brain circuitry in a functional state.
To conduct the study, researchers divided mice in four groups: well-rested group received 6 to 8 hours of sleep; spontaneously awake group received intermittent sleep; acute sleep-deprived group was kept awake for an extra 8 hours; chronic sleep-deprived group was sleep –restricted for 5 days.
Using serial block-face scanning electron microscopy, researchers then took images of synapses and astrocytic processes from the frontal cortex of mouse brain.
After analyzing images, they found that astrocytic phagocytosis, a process similar to microglial phagocytosis, increased after acute and chronic sleep deprivation to take part in cleaning synaptic components of mainly large or heavily used synapses.
“We show for the first time that portions of synapses are literally eaten by astrocytes because of sleep loss,” says Bellesi.
Using confocal microscopy, they observed increased microglial activation and elevated microglial phagocytosis only after chronic sleep deprivation. As suggested by researchers, such low level prolonged microglial activation after chronic sleep loss can make brain more prone to any secondary damage.
As Michele Bellesi told New Scientist, astrocytic phagocytosis associated with short term sleep loss may be beneficial in priming brain connection by removing old synapses.
“They are like old pieces of furniture, and so probably need more attention and cleaning,” says Bellesi.
However, sustained microglial activation associated with chronic sleep loss is worrisome as it might lead to potential brain disorders.
“We already know that sustained microglial activation has been observed in Alzheimer’s and other forms of neurodegeneration,” Bellesi says.
Findings of this study can explain why lack of sleep is associated with neurological disorders, such as Alzheimer’s disease, says Agnès Nadjar of the University of Bordeaux in France.
However, it is not clear from the study whether getting enough sleep can reverse the effects of some sleepless nights. Researchers now plan to figure out how long these effects of sleep deprivation last.
The study has been published recently in the Journal of Neuroscience.