Stressed to the max? Deep sleep can rewire the anxious brain
A sleepless night can trigger up to a 30 percent rise in emotional stress levels, new study shows
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Deep sleep concept (stock image). Credit: © stokkete / Adobe Stock
November 4, 2019
Science Daily/University of California - Berkeley
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 synchronized, and heart rates and blood pressure drop.
When it comes to managing anxiety disorders, William Shakespeare's Macbeth had it right when he referred to sleep as the "balm of hurt minds." While a full night of slumber stabilizes emotions, a sleepless night can trigger up to a 30% rise in anxiety levels, according to new research from the University of California, Berkeley.
UC Berkeley 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 synchronized, and heart rates and blood pressure drop.
"We have identified a new function of deep sleep, one that decreases anxiety overnight by reorganizing connections in the brain," said study senior author Matthew Walker, a UC Berkeley professor of neuroscience and psychology. "Deep sleep seems to be a natural anxiolytic (anxiety inhibitor), so long as we get it each and every night."
The findings, published today, Nov. 4, in the journal Nature Human Behaviour, provide one of the strongest neural links between sleep and anxiety to date. They also point to sleep as a natural, non-pharmaceutical remedy for anxiety disorders, which have been diagnosed in some 40 million American adults and are rising among children and teens.
"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, a postdoctoral fellow in the Center for Human Sleep Science at UC Berkeley.
In a series of experiments using functional MRI and polysomnography, among other measures, Simon and fellow 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 centers were overactive.
"Without sleep, it's almost as if the brain is too heavy on the emotional accelerator pedal, without enough brake," Walker said.
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.
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.
Moreover, in addition to the lab experiments, the researchers conducted an online study in which they tracked 280 people of all ages about how both their sleep and anxiety levels changed over four consecutive days.
The results showed that the amount and quality of sleep the participants got from one night to the next predicted how anxious they would feel the next day. Even subtle nightly changes in sleep affected their anxiety levels.
"People with anxiety disorders routinely report having disturbed sleep, but rarely is sleep improvement considered as a clinical recommendation for lowering anxiety," Simon said. "Our study not only establishes a causal connection between sleep and anxiety, but it identifies the kind of deep NREM sleep we need to calm the overanxious brain."
On a societal level, "the findings suggest that the decimation of sleep throughout most industrialized nations and the marked escalation in anxiety disorders in these same countries is perhaps not coincidental, but causally related," Walker said. "The best bridge between despair and hope is a good night of sleep."
https://www.sciencedaily.com/releases/2019/11/191104124140.htm
Sleep And Memory
January 3, 2017
By Anne Foy, Guest Contributor
For some years now, the world appears to have seen sleep as an inconvenience. Sure, we acknowledge that it’s something which needs to happen. We’re even aware of the dire consequences [1] of not getting enough sleep [2]. But we nonetheless try to push it to the margins of our existence. We force ourselves out of bed before we’re fully awake, and, at the other end of the day, bludgeon our exhausted brains into keeping us awake for longer. We stifle sleep with caffeine, or bring it on artificially with pills [3]. We try to make it into our servant, to be called upon at times of our choosing and hidden away when not wanted. Little wonder that so many of us are struggling with sleep disorders. However, poor sleep does a lot more than simply make us feel groggy and slow. Over time, chronic lack of sleep can have a very serious impact upon your cognition. In particular, sleep is associated with good memory function - so much so that disordered sleeping habits are associated with dementia.
More Than Just ‘Recharging’ Time
There is a common misconception that sleep is about ‘switching off’ in order to ‘recharge’. Humans aren’t cellphones, however. We’re far, far more complicated than that. Sleep is in fact the time when your body and mind carries out some of its most complex operations - the kind of thing it doesn’t want your conscious mind and day to day life interrupting. This is why doctors and healthcare providers [4] are eager for patients to sleep well - without good sleep, a lot of these vital health and maintenance operations go undone, leading to myriad health issues down the line. One of these vital operations is the sorting and processing of memories. We’ve known for a long time that sleep plays an incredibly important role in healthy memory, but haven’t been entirely sure precisely what it does or how it does it. Recently, however, a lot of facts about sleep and memory have been discovered [5] - and revealed serious implications about lack of sleep and cognitive decline.
Deep Sleep Neuron Connections
When we’re in deep, ‘slow-wave’ sleep, our brains effectively ‘replay’ what we’ve experienced during the day. As we’re asleep, it’s able to do this without cognitive interruption, and therefore ‘concentrate’ (for want of a better word) on what it’s experienced. During deep sleep, scientists have observed [6] brains making lots of new connections between neurons. New connections forming between neurons is what ‘learning’ looks like from a neurobiological perspective. From a psychological perspective, ‘learning’ involves taking memories, extrapolating from them, and then storing those memories in ‘long-term’. This is the process the scientists observed occurring in the brains of sleeping subjects.
Lack Of Sleep And Dementia
Quite obviously, if your brain uses its deep sleep time to sort through, store, and learn from memories, a lack of deep sleep is going to cause issues with memory. However, it seems to go a lot deeper than the odd spate of simple forgetfulness. Studies show that disturbed sleep patterns can significantly increase one’s chances of developing dementia. As yet, nobody is entirely sure why this should be the case, but the facts are indisputable [7], and many are reasonably sure that it has something to do with sleep’s role in memory formation. Some speculate that lack of usage during deep sleep causes the brain's memory-retention functions to degrade. Others believe that lack of sleep generally puts an inordinate amount of strain on the brain, causing cell death and therefore cognitive decline.All in all, whatever is actually going on inside the skull, if you want to learn more, remember more, and generally maintain good cognitive health, it’s best to sort out your sleep cycle - and quickly!
[1] Think!, “Fatigue”, UK Government
[2] Mercola, “How Dangerous Is Sleep Deprivation, Really?”, Mar 2014
[3] Ny Daily News, “CDC: 9 million Americans use prescription sleeping pills”, Aug 2013
[4] Q, "health cover"
[5] James Gallagher, “Sleep’s memory role discovered”, BBC, Jun 2014
[6] Guang Yang, Cora Sau Wan Lai, Joseph Cichon, Lei Ma, Wei Li, Wen-Biao Gan, “Sleep promotes branch-specific formation of dendritic spines after learning”, Science, Jun 2014
[7] Caroline Cassels, “Disturbed Sleep Linked To Increased Dementia Risk”, Medscape, Jul 2014