Sunday November 17, 2019

Deep Sleep Calms Down a Stressed Brain

Researches found that deep sleep can calm down and reset the anxious brain

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Deep sleep
A slow-wave sleep can calm and reset the anxious brain. Pexels

Researchers have found that the type of sleep most apt to calm and reset the anxious brain is deep sleep, also known as non-rapid eye movement (NREM) slow-wave sleep, a state in which neural oscillations become highly synchronised, and heart rates and blood pressure drops.

A sleepless night can trigger up to a 30 per cent rise in anxiety levels, researchers from the University of California said.

“We have identified a new function of deep sleep, one that decreases anxiety overnight by reorganising connections in the brain,” said study senior author Professor Matthew Walker.

“Deep sleep seems to be a natural anxiolytic (anxiety inhibitor), so long as we get it each and every night,” Walker added.

“Our study strongly suggests that insufficient sleep amplifies levels of anxiety and, conversely, that deep sleep helps reduce such stress,” said study lead author Eti Ben Simon.

Deep Sleep
Deep sleep helps in restoring the brain’s prefrontal mechanism that regulates our emotions. Pexels

In a series of experiments using functional MRI and polysomnography, among other measures, researchers scanned the brains of 18 young adults as they viewed emotionally stirring video clips after a full night of sleep, and again after a sleepless night.

Anxiety levels were measured following each session via a questionnaire known as the state-trait anxiety inventory.

After a night of no sleep, brain scans showed a shutdown of the medial prefrontal cortex, which normally helps keep our anxiety in check, while the brain’s deeper emotional centres were overactive.

After a full night of sleep, during which participants’ brain waves were measured via electrodes placed on their heads, the results showed their anxiety levels declined significantly, especially for those who experienced more slow-wave NREM sleep.

“Deep sleep had restored the brain’s prefrontal mechanism that regulates our emotions, lowering emotional and physiological reactivity and preventing the escalation of anxiety,” Simon said.

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Beyond gauging the sleep-anxiety connection in the 18 original study participants, the researchers replicated the results in a study of another 30 participants.

Across all the participants, the results again showed that those who got more nighttime deep sleep experienced the lowest levels of anxiety the next day.

The finding was published in the journal Nature Human Behaviour. (IANS)

Next Story

Immune Cells Become Active and Repair Brain While Sleep: Study

For the findings, researchers conducted the study on mice

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Sleep
Study suggests that the enhanced remodeling of neural circuits and repair of lesions during Sleep may be mediated in part by the ability of microglia to dynamically interact with the Brain. Pixabay

Researchers have found that immune cells called microglia, which play an important role in reorganising the connections between nerve cells, fighting infections, and repairing damage, are also primarily active while we sleep.

Microglia serve as the brain’s first responders, patrolling the brain and spinal cord and springing into action to stamp out infections or gobble up debris from dead cell tissue.

“This research shows that the signals in our brain that modulate the sleep and awake state also act as a switch that turns the immune system off and on,” said study lead author Ania Majewska, Professor at University of Rochester in the US.

In previous studies, Majewska’s lab has shown how microglia interact with synapses, the juncture where the axons of one neuron connects and communicates with its neighbours.

The microglia help maintain the health and function of the synapses and prune connections between nerve cells when they are no longer necessary for brain function.

For the findings, researchers conducted the study on mice.

The current study points to the role of norepinephrine, a neurotransmitter that signals arousal and stress in the central nervous system.

This chemical is present in low levels in the brain while we sleep, but when production ramps up it arouses our nerve cells, causing us to wake up and become alert.

The study showed that norepinephrine also acts on a specific receptor, the beta2 adrenergic receptor, which is expressed at high levels in microglia.

When this chemical is present in the brain, the microglia slip into a sort of hibernation.

Sleep
Researchers have found that immune cells called microglia, which play an important role in reorganising the connections between nerve cells, fighting infections, and repairing damage, are also primarily active while we Sleep and affects Brain. Pixabay

The study, which employed an advanced imaging technology that allows researchers to observe activity in the living brain, showed that when mice were exposed to high levels of norepinephrine, the microglia became inactive and were unable to respond to local injuries and pulled back from their role in rewiring brain networks.

“This work suggests that the enhanced remodeling of neural circuits and repair of lesions during sleep may be mediated in part by the ability of microglia to dynamically interact with the brain,” said study first author Rianne Stowell.

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“Altogether, this research also shows that microglia are exquisitely sensitive to signals that modulate brain function and that microglial dynamics and functions are modulated by the behavioural state of the animal,” Stowell said.

The study was published in the journal Nature Neuroscience. (IANS)