Introduction
Among Americans, approximately 50 to 70 million suffer from a sleep disorder. Sleep problems adversely impact both children and adults concerning their daily functioning and overall health. Several research studies have increasingly reported the importance of sleep; connecting a lack of sleep with immune deficiencies, depression, cognitive deficits and risk to obesity. (Bellesi, Tononi, Cirelli, & Serra, 2015; Johnsen, 2013; Walker & Stickgold, 2014). Recent literature has supported the robust correlation between sleep and mental health(Johnsen, 2013; Peppard et al., 2013; Sekhon & Strohl, 2014; Walker & Stickgold, 2014). The majority of psychiatric disorders are linked to sleep disturbances. In the past, researchers believed that sleep issues were a result of mental disorders, whereas new research indicates that the lack of sleep is leading to psychological disturbances(Sekhon & Strohl, 2014; Walker & van Der Helm, 2009). Considering the high rate of sleep disorders and associated adverse health outcomes, interventions to remedy sleep issues are warranted as a public health concern
Sleep Cycles: Adults and Children
An individual will go through five phases of sleep during sleep duration. This includes five stages: 1, 2, 3, 4, and rapid eye movement (REM)(Walker & Stickgold, 2014). An individual begins in phase 1 and eventually reaches REM sleep, and the cycle is repeated. Approximately half of the sleep duration is in stage 2. The remaining time sleeping will be spent in 30%(1, 3, and 4) and REM sleep (20%)(Bellesi et al., 2015; Walker & Stickgold, 2014). Infants differ from adults in that they spend 50% in REM sleep. Stage 1 is a very light sleep, and stage 2 is where the brain activity slows down, and eye movements dissipate(Bellesi et al., 2015). Phases 3 and 4 are considered deep sleep and people are often unable to wake during this time. No eye movement or muscle activity is present during these periods(Bellesi et al., 2015; Walker & Stickgold, 2014). Children may experience night terrors or sleepwalking when awakened during stages 3 and4. The last phase, REM sleep, breathing is shallow and irregular, our eye movement speed up along with our heart rate and blood pressure(Altevogt & Colten, 2006; Hillman, Singh, McArdle, & Eastwood, 2014).
The first REM sleep stage will begin around 70 to 90 minutes into sleep duration(Bellesi et al., 2015; Walker & Stickgold, 2014). Sleep cycles are estimated to be 90 to 110 minutes to complete, with the first cycle entailing a REM sleep which is quite short and then increases as the cycles(Bellesi et al., 2015; Walker & Stickgold, 2014). Wakefulness is caused by neurotransmitter signals in the brain, factors that resulted in an imbalance of these signals will determine the ability to be cognitively sharp. (Bellesi et al., 2015; Walker & Stickgold, 2014)Young infants are recommended and often have 16 hours a day, and about 9 hours for adolescents, and 7-8 hours among adults.
Since the time of sleep decreases as age increases, older people (65+) are diagnosed at a higher rate of insomnia(Peppard et al., 2013). Sleep is vital to our mental stability and mood(Altevogt & Colten, 2006; Bellesi et al., 2015; Walker & Stickgold, 2014). Sleep increases the amount of neurons need for repair(Altevogt & Colten, 2006). Thus, without sleep neurons are unable to maintain normal cellular activities causing abnormalities Deep sleep is especially important as it implicated that this type of sleep fosters emotional and social functioning(Baglioni, Spiegelhalder, Lombardo, & Riemann, 2010; Walker & Stickgold, 2014). Insomnia has been cited as a source of exasperating the adverse effects of psychiatric disorders in a bi-directional manner(Gregory, Rijsdijk, Lau, Dahl, & Eley, 2009; Sekhon & Strohl, 2014; Walker & Stickgold, 2014).
Prevalence & Impact of Sleep Problems: Adults & Children’s’ Mental & Physical Health
Sleep problems in young children can have life-long implications. There is strong evidence that sleep problems occur before psychiatric disorders, particularly major depression (Baglioni et al., 2010; Gregory et al., 2009; Johnsen, 2013; Sekhon & Strohl, 2014; Walker & van Der Helm, 2009). Considering this seemingly causal relationship, sleep problems among children should be identified to prevent the development of poor mental health conditions. Sleep-disordered breathing (SDB) and behavioral sleep problems (BSP) are most pernicious, adversely impacting the development of social-emotional , cognitive and communication skills(Mindell & Owens, 2015; Schwichtenberg et al., 2013).
Recent trials find that induced sleep restriction impairs emotional regulation in healthy toddlers, school-aged children, and neurobehavioral function in school-aged children with ADHD(Byars, Yolton, Rausch, Lanphear, & Beebe, 2012; Mindell & Owens, 2015; Schwichtenberg et al., 2013). Both BSPs and SDB peak in prevalence between 2 - 6 years of age(Byars et al., 2012; Mindell & Owens, 2015). During this period, ≈10-30% of children have BSPs , 2-4% have apnea, and up to 21% habitually snore. (Byars et al., 2012; Mindell & Owens, 2015; Schwichtenberg et al., 2013)..BSPs and SDB are highly co-morbid; 25%-40% of children with SDB symptoms have BSP, and vice-versa(Moore & Bonuck, 2013).Children’s nighttime awakenings may, in fact, be preceded by under-identified respiratory events, as are adults(Mindell & Owens, 2015; Peppard et al., 2013). Pediatric sleep disorders impact behavioral, cognitive and physical development, as well as the quality of life(Mindell & Owens, 2015; Schwichtenberg et al., 2013; Walker & van Der Helm, 2009). Disruptions in normal sleep continuity, impact brain, metabolic and endocrine function, and normal gas exchange. In children, the two most common types are 1) difficulties initiating or maintaining sleep (DIMS), and 2) sleep disordered breathing (SDB)(Mindell & Owens, 2015; Moore & Bonuck, 2013).
The term “sleep problems” denotes the following two types: DIMS and SDB. An American Academy of Sleep Medicine review notes the distinction between clinical diagnoses and research definitions of sleep problems. In early childhood, the two most prevalent sleep problems leading to inadequate or fragmented sleep are 1) dyssomnias and 2) sleep-related breathing disorders (SDB). Dyssomnias occur in 25-40% of typically developing preschool aged children (American Academy of Sleep Medicine , 2005; Mindell & Owens,2015) The “Difficulties Initiating and Maintaining Sleep”(DIMS) are most pertinent to the following types of diagnoses listed in the International Classification of Sleep Disorders 2nd ed. (ICSD-2) : Behavioral Insomnias of Childhood (e.g., limit-setting sleep type, sleep onset association type); Circadian Rhythm Disorders (e.g., delayed sleep phase type, irregular sleep-wake phase type), and Inadequate Sleep Hygiene diagnosis(Mindell & Owens, 2015). The symptoms of DIMS impact adults and children; they result in inadequate and fragmented sleep which in turn, can have severe behavioral and cognitive consequences(Mindell & Owens, 2015; Schwichtenberg et al., 2013).
Sleep Disordered Breathing (SBD) refers most commonly to obstructive sleep apnea, believed to affect at least 2-3% of all children(Moore & Bonuck, 2013) and-and 7% of adults (Peppard et al., 2013). SBD is rising in adults ranging from an estimated 14% to 55% varying based on age group(Peppard et al., 2013). SDB peaks between the ages of 2-6, given the relative adenotonsillar hypertrophy found at this time, but it is also found in younger children(Byars et al., 2012; Moore & Bonuck, 2013). In general populations, ≈10-30% of toddlers and preschoolers experience DIMS (Moore & Bonuck, 2013). Sleep apnea is found among 18 million Americans adults, and many have gone undiagnosed(Peppard et al., 2013). Common characteristics of sleep apnea are loud snoring. During obstructive sleep apnea episodes, air flow is blocked and oxygen level decrease. Consequentially, the person awakens with extenuated upper airway muscles; SDB has significant adverse effects on mental health, cognition, and growth(Moore & Bonuck, 2013; Peppard et al., 2013).
Among general pediatric patients, SDB rates of those with visits for “developmental/ psychiatric” reasons were double that of the entire sample (Byars et al., 2012; Mindell & Owens, 2015). Most pediatric primary care providers don’t screen for SDB. When SDB is discussed, it is rarely addressed(Byars et al., 2012). Thus, warranting the need for public heath interventions focused on remedying sleep disorders to reduce negative affects among these populations. The NIH states: “Recognition of the link between sleep disturbances and neurobehavioral disorders in childhood, such as attention deficit hyperactivity disorder (ADHD), has major public health implications for both the treatment and prevention of psychiatric co-morbidity.”(Health, 2010; Mindell & Owens, 2015)
A national longitudinal study of Canadian 2- 3-year-olds (n≈9,000 children; 3 waves) found that DIMS-type problems were as strong a correlate of internalizing (i.e., anxiety) and externalizing (i.e., hyperactivity/aggression) problems as well-established risk factors (i.e., parenting and maternal depression)(Reid, Hong, & Wade, 2009). Furthermore, the relationship between sleep problems and internalizing and externalizing problems was independent of relations with these risk factors(Reid et al., 2009). Nearly all neuro-behavioral and neurocognitive conditions of childhood are potentially linked to sleep problems and is likely to be bidirectional(Mindell & Owens, 2015; Reid et al., 2009; Schwichtenberg et al., 2013).For example, children with autism spectrum disorders have disruptions in GABA and melatonin, which both regulate sleep(Mindell & Owens, 2015). Conversely, their psychiatric symptoms may interfere with sleep initiation(Mindell & Owens, 2015; Sekhon & Strohl, 2014). Both SDB and DIMS cause disrupted and inefficient sleep. Both result in non-specific signs and symptoms, e.g.: mood changes; excessive daytime sleepiness; fatigue and somatic complaints, and; cognitive impairment and poor school or work performance related to excessive sleepiness, negative mood, and fatigue (Mindell & Owens, 2015; Moore & Bonuck, 2013; Peppard et al., 2013; Schwichtenberg et al., 2013; Sekhon & Strohl, 2014; Walker & van Der Helm, 2009)
SDB is a manifestation of anatomical processes (e.g., airway narrowing), local tissue compliance, and neurophysiological contributions(Altevogt & Colten, 2006). In contrast, DIMS in toddlers and young children arises from a confluence of biological, circadian, and neuro-developmental factors, and environmental and behavioral variables. Sleep ecology (i.e. where child slept) and parental behaviors (i.e., night feeding upon waking) explain much of the variance in young children’s sleep patterns (Mindell & Owens, 2015) .My own search of the SDB-related terms “apnea” + “cognitive” + “children” in PubMed yields 92 abstracts, including several systematic reviews and meta-analyses. The most comprehensive review (61 studies, 2006) finds “strong evidence that childhood SDB is associated with deficits in behavior and emotional regulation, scholastic performance, sustained attention, selective attention.” (Beebe, 2006)Notably, 8.8% of parents report that their school-age child was diagnosed with ADD/ADHD, and 11.5% reported a learning disability(Beebe, 2006). There is also evidence that are deficits persisting into the teenage and adult years(Beebe, 2006; Mindell & Owens, 2015; Peppard et al., 2013).
A study published in Current Biology examined the relationship between sleep and mental health among students. The main areas of the brains linked to sleep were explored: the amygdala and the midbrain that decodes feelings(Walker & van Der Helm, 2009). Comparison of MRI imaging was made, those who were sleep deprived illustrated ~60 % increased activity compared to normal population, with five times more neurons among those with less sleep(Walker & van Der Helm, 2009). Among the sleep-deprived group, the amygdala appeared to be "rewired" interacting with an area of the brain that triggers fight or flight, thus evoking irritability and anxiety(Walker & van Der Helm, 2009). The causal relationship is a difficult claim to make but to increase evidenced by impaired sleep, and psychiatric symptoms are likely.
Another study was able to attribute attention deficit hyperactivity disorder and depression to the presence of sleep apnea; a sleep disorder that results in disturbed breathing patterns(Beebe, 2006; Sekhon & Strohl, 2014). Researchers explain that the medial frontal regions of the brain that tell the body to rest are being overused and depleted as a result of sleep deprivation, compromising ability to sleep in the future(Altevogt & Colten, 2006; Beebe, 2006; Sekhon & Strohl, 2014; Walker & van Der Helm, 2009). It is like a vicious cycle, once you are sleep deprived the circuits in the brain tied to sleep become overworked, and this comprises the effectiveness of this part of the brain to help one sleep. The emotional and social impact of this inability to sleep is further supported by studies examining the effects of abnormal REM and slow wave sleep patterns(Altevogt & Colten, 2006; Mindell & Owens, 2015; Reid et al., 2009; Schwichtenberg et al., 2013; Walker & van Der Helm, 2009).
An adequate amount of REM sleep is associated with several medical conditions(Altevogt & Colten, 2006; Johnsen, 2013; Mindell & Owens, 2015; Peppard et al., 2013). The required amount of REM sleep is needed to ward off seizures(Altevogt & Colten, 2006; Beebe, 2006). The neuron responsible for sleep also affects immunity. Strokes and asthma attacks are more frequent as a result of their connection to sleep-related hormones, and sleep’s impact on heart rate. REM sleep allows for increased production of proteins needed to for mental stability (Altevogt & Colten, 2006).
Circadian rhythms are defined as the changing patterns of mental and physical states experienced during the day; this influences one's sleep drive and most commonly is strongest during 2-4am (Altevogt & Colten, 2006; Johnsen, 2013; Walker & Stickgold, 2014). The physiological processes associated with REM sleep and Non-rapid eye movement sleep (NREM) are presented in Table 1 (Altevogt & Colten, 2006). As you can see these processes influence loss of muscle tone and reflexes which are crucial for mental health as it functions to prevention “acting out” resulting in distress during sleep and while awake(Altevogt & Colten, 2006). The physiological changes reported in Table 1, do not typically impact healthy adults but do cause an in imbalance or those with compromised mental and physical health.
The hours of sleep one can achieve a strong determinant of the symptomology of mental disorder(Mindell & Owens, 2015; Sekhon & Strohl, 2014). Among adolescents, a study yield results concluding that poor mental health status was found more frequently among those who slept less than 7 hours, compared to 9hrs+ of sleep(Kaneita et al., 2007). Furthermore, insomnia symptoms were correlated with hours of sleep. Insomnia is characterized by an inability to initiate or maintain sleep or frequent waking resulting in lethargy (Altevogt & Colten, 2006; Kaneita et al., 2007; Mindell & Owens, 2015). Sleep is the recovery time for our minds to process the stressors of the day and rejuvenate. Daytime alertness and memory are linked and when impaired by obtaining less than 7 hours sleep are severely compromised(Kaneita et al., 2007). This study provided future support to the importance of sleep in forming memories, which is critical to one’s mental health.
Reports of severe sleep deprivation among those with a mental condition can cause psychosis, in which the patient experiences increased paranoia and hallucinations(Altevogt & Colten, 2006; Baglioni et al., 2010; Sekhon & Strohl, 2014; Walker & Stickgold, 2014). Among healthy adults, inadequate sleep can evoke manic episodes of agitation and hyperactivity. Sleep problems are comorbid with depression as well as schizophrenia. Those with either depression or schizophrenia have reported waking early hours in the evening and are unable to return to sleep(Sekhon & Strohl, 2014). Furthermore, the frequent awakenings cause increased sleepiness and have been associated with mood changes and depressive symptoms(Gregory et al., 2009; Sekhon & Strohl, 2014). Physicians of psychiatric practice report that 50 to 80% of their patients have sleep problems, whereas only 10 to 18% are found in the general population(Sekhon & Strohl, 2014; Staff, 2010).
Conclusion:
As illustrated above, there is substantial evidence of sleep problems increasing the risk of developing mental illnesses (depression, bipolar and anxiety). Psychiatric disorders and sleep problems demonstrate a bidirectional relationship. Considering this, the treatments of sleep disorder have the potential to relieve symptoms associated with mental health issues. Treatment for sleep problems includes behavioral interventions and medications. Considering the adverse impact sleep problems have on both adults and children, and worsened among vulnerable populations, sleep hygiene is a necessary component of primary care. Primary care providers should be trained in proper sleep hygiene (regular sleep schedule, disengaging from technology before sleep, etc.), and further behavioral research should be conducted to address this widespread public health concern.
References:
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