Deep sleep calm and reset the anxious brain

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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.

This shows the location of the mPFC

Study shows that a sleepless night boosts anxiety levels up to 30%. The image is credited to Eti Ben Simon and Matthew Walker.

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.”


Optimum quality and quantity of sleep regulates our core biological functions.1,2 Although the amount of time a person is engaged in sleep is important, reaching the deep rejuvenating stages of sleep is essential for optimum health benefits.1,2 Sleep quality reflects how well a person is able to fall asleep, cycle through the various stages of sleep, and stay in those sleep stages for their full duration.1,2

 Often, manifestations of poor sleep are misinterpreted as behavioral issues, cognitive dysfunction, and/or systemic health concerns that may present differently in children and adults.1,3,4 

The National Sleep Foundation estimates that 50 to 70 million Americans are affected by chronic sleep disorders or sleep disruptions that can significantly affect health and safety.5 

The Centers for Disease Control and Prevention (CDC) has declared sleep deprivation a public health crisis.6 

The key sleep disorders listed by the CDC include insomnia, narcolepsy, restless leg syndrome, and sleep apnea (Table 1).6 Sleep deprivation, regardless of the cause, has been shown to cause complex oral, systemic, and cognitive health issues resulting in poor health-related quality of life and decreased work productivity.15

Table 1

Examples of Sleep Related Conditions and Disorders

Poor Sleep Quality Conditions or DisordersSigns, Symptoms or Factors Related to Poor Sleep Quality
Sleep HygieneExtrinsic factors such as electronics; blue-light; day-light; disruptions from people or pets; caffeine; adenosine receptor antagonist medications; sleep position.1,6,7,8,9
Sleep behavior disorderPerson acts out his or her dreams; includes talking, yelling, punching, jumping from bed, arm flailing and grabbing.6,10
Melatonin irregularities
Circadian rhythm disruptions
Persistent or recurrent patterns of sleep disturbance due to outside factors such as jet lag or shift work. Internal factors such as problems with melatonin release or other abnormalities with the circadian system.2,5,6,11,12
InsomniaDifficulty falling asleep and/or staying asleep for a full sleep cycle.5,6
NarcolepsyExtreme daytime sleepiness combined with muscle fatigue and weakness.5,6
Restless Leg SyndromeCrawling feeling under skin of lower legs and uncontrollable urge to move legs. Symptoms are usually worse at night.5,6
Obstructive Sleep ApneaAirway collapses during the sleep cycle, preventing normal breathing, causing lack of oxygen to the brain, preventing the individual from reaching deep sleep along with body and brain repair.1,5,6,13,14

Oral health professionals are in the optimal position to detect a sleep quality concern due to the oral presentation of individuals suffering from chronic poor sleep issues.16,17 When poor sleep is suspected, it is the responsibility of oral health clinicians to refer patients to an appropriate allied health professional.18,19 

The American Dental Association has adopted a formal policy statement that states dentists are to include screening for sleep-related breathing disorders during all oral examinations.18 

Dentists are also responsible for referring at-risk patients to a primary care provider and work with that provider and the patient to determine the best course of action for that patient.18 

The American Dental Hygienists’ Association also recognizes the dental hygienists’ ability and responsibility to identify oral and systemic health relationships and refer patients to the appropriate allied health professional for a patient to obtain optimal health outcomes.19 

Although oral health professionals are providing assessments that can lead to detection of a serious sleep quality concern, shortcomings with identifying sleep disorders in oral health education programs might prevent oral health practitioners from connecting oral health assessments and whole health indictors to a poor sleep quality conclusion.20 

Even if a sleep quality concern is suspected, there is a general lack of communication and support between medical and dental teams to provide a continuity of care for patients.21,22

The oral health assessment process performed by a dentist or dental hygienist is often the first time a sleep quality concern is recognized by a health care provider.

Training received by oral health professionals includes obtaining medical and dental histories, identifying abnormal oral structures, detecting oral disease, identifying oral/systemic health links and, more specifically, identifying signs and symptoms of sleep-related bruxism, primary snoring, and obstructive sleep apnea (OSA).19,20 

Dental providers already provide many medically-related chairside screenings for patients including hypertension, diabetes mellitus, obesity, human papilloma virus, and oral side effects from cancer treatments, with hypertension screening being the most prevelent.23 

Dental providers report a willingness to conduct medical screenings granted the providers were well trained in the medical condition, screening process, and the screening was time and cost effective.23 

Early detection of an oral health and systemic health-related condition, such as a sleep disorder or poor sleep condition, has the potential to reduce comorbidities associated with poor sleep health.5,6

Poor sleep quality can be a multifactorial situation and/or condition(s) that can be affected by a person’s sleep environment, physiological features related to systemic health, oral myofunctional disorders, restricted airway, and/or chemical and electrical imbalances related to melatonin or circadian rhythm.1,3,7,8,11,16,24,25 

Sleep deprivation, including OSA, does not discriminate according to age, gender, or body composition.

OSA is not often identified in childhood, because the severity of signs and symptoms tend to increase through developmental growth into adulthood.16,25 

Research suggests oral structure formation and health concerns can put men, women, and children at risk for a poor sleep situation that needs to be identified and addressed.5,6,11,16,26,27

This paper will assist the oral health professional in recognizing the relationship between sleep and health, identifying sleep quality concerns in relation to oral health assessments, disseminating sleep quality assessments, and determining appropriate referrals for sleep quality issues.

SLEEP PROCESS

While sleeping, an individual’s mind and body are performing very specific functions that are vital to the regulation, maintenance, and repair of specific body systems.1,2 

Each of the three non-rapid eye movement (NREM) stages of sleep serve a specific function to quiet body and brain, lower body temperature, and slow heart rate to prepare the body and organ systems for maintenance and repair.1,2 

The rapid eye movement (REM) stage of sleep allows the mind to transfer new memories and lessons to long-term memory, rationalize emotions, and is vital for brain repair and maturation.1,2

 A quality sleep event includes five to six specific cycles of the various NREM and REM stages over a 7- to 9-hour period.2 

Each cycle is different from the last and serves a different purpose.2 As the sleep event progresses, a person spends more time in REM sleep and less time in the NREM stages.1,2

 Each time a person experiences a sleep arousal or is pulled out of the deep stages of sleep, they are prevented from obtaining rejuvenation of the body and brain needed to achieve or maintain optimal health.1,2 

Sleep arousals can be caused by poor sleep hygiene, restricted airway, systemic health issues, or cognitive health issues.14

Systemic Health Concerns Related to Poor Sleep

Due to the role sleep quality has on body and brain repair and rejuvenation many health risks can be factors that either contribute to poor sleep, are caused by poor sleep, and/or are exacerbated by poor sleep. A bidirectional relationship appears to exist between various health concerns and sleep quality.1,11,12,27,28 A strong correlation between hypertension, cardiovascular disease, and stroke compared with the quality and quantity of sleep has been consistently shown in literature.29 

Children who have undiagnosed and untreated sleep disruptions and/or sleep disorders are also at increased risk for hypertension.30 Type II diabetes has been shown to have a relationship with chronic sleep arousals.31 

When an individual is not reaching the N3 stage of sleep or staying in this stage for an adequate amount of time, glucose and insulin regulation is altered.32 Obesity has a cyclical relationship with poor sleep quality and hormone and metabolism regulation.32

 Overweight persons are at a higher risk for airway obstruction upon reaching N3 stages of sleep, resulting in poor regulation of metabolic hormones.28 To continue the cycle of poor sleep and obesity, individuals who are sleep deprived are more likely to make unhealthy food choices and consume more calories during the day in an effort to increase energy levels.33 

Open-mouth breathing, obesity, and poor sleep quality conditions and disorders have been correlated with a higher risk for developing gastroesophageal reflux (GERD) and other esophageal conditions.34 

Sleep-disordered breathing and asthma have been correlated, as both are inflammatory disorders of the upper and lower airways and can contribute to respective worsening of each condition and possibly lead to OSA.27 

To make matters more complicated, many of the medications used to treat sleep-related medical conditions contribute to poor sleep due to the type of receptor antagonist effect in the brain.2 According to the National Sleep Foundation, medications taken to treat nasal congestion, hypertension, heart disease, thyroid disorders, birth control, breathing issues, and cognitive health concerns can contribute to difficulty with falling and/or staying asleep.5

In the past, middle-aged men were mostly likely to be suspected for a poor sleep quality concern; however, researchers now know women are also at equal risk for poor sleep quality concerns as men but for different reasons.26,29 

Health-related sleep disruptors for women can be related to hormone changes during pregnancy, pregnancy complications, and hormone changes after menopause.26,29

 Poor sleep factors that affect men, women, and children, such as poor sleep hygiene, systemic health issues (eg, asthma, allergies, obesity), and sleep disorders can exacerbate sleep quality concerns for females.26,29

Cognitive Health Concerns Related to Poor Sleep

An individual who is unable to reach the brain repair and rejuvenation stage of sleep called REM is at risk for cognitive health issues. Individuals who are unable to reach and maintain REM sleep have been shown to be at greater risk for attention deficit disorder, bipolar disorder, depression, anxiety, emotion control, cognitive flexibility, and memory processing.

Individuals suffering from post-traumatic stress disorder have been shown to have difficulty reaching and maintaining REM sleep, which in turn makes management of this disorder more difficult.4 Many other systemic and cognitive health concerns related to poor sleep exist that are beyond the scope of this paper (Table 2).

Table 2

Sleep Stages and Health Effects

Sleep StagePhysiological responsePhysical ResponseLong-Term Health Effects
N1Mind and body start to relaxBreathing and heart rate are regularComment: Does not occur in Newborn babies or during a narcoleptic event.1,2,5,6
Easy to wake
Aware of surroundings
N2RelaxedSteady breathing/heart rate.Long-term memory health1,2,5,6,11,16
Unaware of surroundingsBody temperature drops
Semi-easy to wakeRelaxation of upper airway
Snoring may begin
Brain spindles related to memory form
N3Deep sleepBlood pressure dropsHypertension
Large skeletal muscles relax significantlyBreathing slowsCardiovascular disease
Difficult to wake someone in this stageBlood supply to muscles increasesType II diabetes
Collapse of upper airway possibleAcid reflux
Circadian rhythm regulationPain management
Tissue growth and repairPoor healing
Energy RestoredLack of energy
Hormone regulationWeight control issues1,2,5,6,11,12,28,36
Glucose tolerance Insulin secretion
Rapid Eye Movement (REM)Brain is very activeEmotional-Memory ProcessingAttention Deficit Hyperactivity Disorder
Occurs approximately 25% of nightProvides energy to brain and bodyDepression
Dreaming occursSupports daytime performanceAnxiety
Skeletal muscles have near complete atoniaPoor memory processing, poor emotion processing26,9,12,37

Source:
UC Berkeley
Media Contacts:
Yasmin Anwar – UC Berkeley
Image Source:
The image is credited to Eti Ben Simon and Matthew Walker.

Original Research: Closed access
“Overanxious and underslept”. Eti Ben Simon, Aubrey Rossi, Allison G. Harvey & Matthew P. Walker.
Nature Human Behaviour doi:10.1038/s41562-019-0754-8.

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