In general, disorders of hypersomnolence include excessive daytime sleepiness of idiopathic origin or idiopathic hypersomnolence, narcolepsy, Kleine–Levin syndrome, and disorders of menstrual hypersomnolence. Other causes of hypersomnolence will be discussed later. Hypersomnolence is characterized by excessive sleepiness during the day and/or prolonged overnight sleep, and initial sleep inertia following sleep (American Academy of Sleep Medicine, 2014; American Psychiatric Association, 2013; Mindell & Owens, 2015). The sleepiness can result in automatic behaviors where the individual completes tasks with little or no recall. Although sleep overnight may be more than adequate (>9 hours), sleep is often nonrestorative. While hypersomnolence disorder is rare in children, many experience excessive daytime sleepiness, which will be the focus of the rest of this section, along with consideration of narcolepsy. It is especially important for the clinician to determine differences between fatigue and sleepiness in the assessment of these children. Children with narcolepsy may fall asleep in unusual places such as at the table or in clinic. Those with idiopathic hypersomnolence will fall asleep but in more usual circumstances such as long car drives and those with fatigue will often deny falling asleep.

Although rare, when narcolepsy does occur in children it is associated with significant impairments in daytime functioning. Narcolepsy is a life-long disorder characterized by excessive daytime sleepiness and cataplexy (American Academy of Sleep Medicine, 2014; American Psychiatric Association, 2013; Mindell & Owens, 2015). Narcolepsy type 1 (NT1), the complete form with cataplexy and/or hypocretin/orexin deficiency, is distinct from narcolepsy type 2 (NT2), without cataplexy or normal hypocretin/orexin levels. Diagnosis is based on clinical assessment and confirmed by PSG followed by MSLT demonstrating abnormal short mean sleep-onset latency (<8 minutes) and the occurrence of two or more sleep-onset REM Periods (SOREMPs). In this circumstance, there will often be REM sleep intrusion into wake, which may account for sleep attacks during the day. The association of daytime sleepiness, sleep attacks, and cataplexy should alert the clinician to the diagnosis of narcolepsy. Other features include hypnagogic hallucinations (vivid dreams at sleep onset or offset) and sleep paralysis which can affect the general population as well. Narcolepsy is generally associated with the HLA class II haplotype DQB1*06:02 in 98% of patients with NT1 and hypocretin/orexin deficiency. HLA DQB1*06:02 is not specific for narcolepsy and is present in healthy individuals in about 26% of the general population. The diagnostic criteria are specific to adult patients and while they are used in children, diagnosis may be delayed while criteria are not yet being met with the evolution of sleep architecture changing in school-aged children and adolescents. It is generally normal for adults to enter REM within 60–90 minutes after falling asleep, however, in people with narcolepsy this is markedly reduced.

Narcolepsy with cataplexy affects 0.02%–0.04% of the population and affects both sexes (American Psychiatric Association, 2013). There are two peak onset periods (15–25 and 30–35 years) (American Psychiatric Association, 2013). Despite this, many may have had symptoms since childhood with many reporting symptoms up to 10 years prior to diagnosis. Recent literature also suggests that if testing is negative then it should be repeated every so often contrary to previous thoughts that one test for narcolepsy was sufficient (Chaplin, Szakács, Hallböök, & Darin, 2017). The recent development of a quality of life measure for young people with narcolepsy that is disease specific will enable more meaningful tracking of therapy outcomes. Cognitive effects are prominent in narcolepsy and recent work suggest that dysregulation in sustained attention is the most commonly reported challenge by patients (Witt et al., 2018). Children with narcolepsy are also at high risk of psychosocial issues such as depression, anxiety, and low self-esteem (Blackwell, Alammar, Weighall, Kellar, & Nash, 2017).

The exact prevalence of narcolepsy in patients with ADHD is unclear but as described in the introduction of this chapter, numerous studies have found that patients with ADHD commonly experience excessive daytime sleepiness as assessed by survey measures as well as more objective measures like MLST (Cortese et al., 2009; Langberg et al., 2017). For example, children with ADHD (n=46) had higher levels of parent-reported daytime sleepiness on the Children’s Sleep Habits Questionnaire compared to children without ADHD (n=46) (Owens, Maxim, & Nobile, 2000), with one study finding stronger relationships between daytime sleepiness and the inattentive presentation of ADHD (LeBourgeois, Avis, Mixon, Olmi, & Harsh, 2004; Mayes et al., 2009). Using MLST, children with ADHD (n=34) were found to be sleepier during the day compared to 32 matched controls (Golan, Shahar, Ravid, & Pillar, 2004). Results from this study suggested that most of the children with ADHD were sleepy, rather than the findings being driven by a small number of very sleepy children (Golan et al., 2004). Daytime sleepiness in ADHD appears to have a detrimental impact on functioning. In a study of 257 children with ADHD aged 5–13 years, teacher-rated daytime sleepiness in children was independently associated with poorer emotional and behavioral functioning even when accounting for sleep problems as reported by parents (Lucas, Mulraney, & Sciberras, 2017). Similarly, Langberg and colleagues found that daytime sleepiness, as opposed to total sleep duration, was a better predictor of parent and teacher-ratings of academic functioning (Langberg, Dvorsky, Marshall, & Evans, 2013).

Patients with narcolepsy appear to also have increased vulnerability to ADHD symptomatology. In a cross-sectional study, ADHD symptoms were evaluated in 108 narcoleptic children and 67 controls under 18 years of age (Lecendreux et al., 2015). Both groups and their families completed questionnaires on ADHD symptoms and daytime sleepiness. Scores showed that children with narcolepsy, treated or not and regardless of type (NT1 or NT2) were twice as likely as controls to have ADHD symptoms. Moreover, the severity of the symptoms was associated with greater sleepiness, tiredness, and insomnia. Sub-domains of inattention, hyperactivity, and impulsivity were also significantly greater among narcoleptics compared to controls but there was no difference between NT1 and NT2 groups. Regarding treatment it appeared that medicated narcoleptic children presented with less symptoms of narcolepsy than untreated ones, but symptoms of ADHD were not attenuated. This suggests ADHD symptoms are poorly improved by psychostimulants or by modafinil in the narcoleptic population.

Daytime sleepiness in children with ADHD may be obscured by excessive motor activity supporting the hypoarousal theory in children with ADHD (Miano, Parisi, & Villa, 2012). This longstanding explanation was proposed in 1993 (Weinberg & Harper, 1993). It posits that hyperactivity is developed as a strategy for ADHD patients to reduce sleepiness and maintain alertness. Furthermore, in a prospective case control study of 15 consecutive patients with ADHD, Miano et al. (2016) discerned various ADHD phenotypes according to association with an hypoarousal state, delayed sleep-onset insomnia, sleep breathing disorders, RLS, or epilepsy. This approach to considering sleep in children with ADHD is relatively novel and should be replicated in future studies using larger sample sizes. This type of approach presents the possibility that the management of patients could differ according to their sleep phenotype. However, whether excessive daytime sleepiness is a primary condition in ADHD symptomatology, a coexisting factor resulting from neurodevelopmental alteration, or simply a consequence of night disturbances proper to ADHD, remains to be elucidated.

In the study by Filardi et al. (2017), distinction between type 1 and type 2 narcolepsy, in which hypocretin/orexin neurons are supposed to be intact or only partially compromised, allows a hypothesis on the role of hypocretin/orexin in the modulation of impulsivity. In fact, the impaired attentional profile in NT1 patients is attributable to a poor stimulation by hypocretin/orexin projections on the noradrenergic structures involved in the maintenance of alertness (Tsujino & Sakurai, 2013).

More broadly, hypocretin/orexin plays the role of a conductor to help orchestrate vigilance, appetite but also endocrine and autonomic functions (Kuwaki, 2015). Hypocretin/orexin neurons involved in wakefulness and arousal are located in the lateral hypothalamus and project to various regions of the central nervous system including cerebral cortex, basal forebrain, and the locus coeruleus in the brainstem (Alexandre, Andermann, & Scammell, 2013). Through their projections to the basal forebrain, these neurons also promote attention. Involvement of the hypocretin/orexin system in attentional processing occurs through enhancement of cortical acetylcholine efflux (Villano et al., 2017).

In line with the deficit in arousal theory in ADHD, the hypothesis that individuals affected with ADHD could have hypoactivation of the hypocretin/orexin neurons implicated in regulation of wakefulness has been suggested (Cortese, Konofal, & Lecendreux, 2008). Additionally, neurons involved in the control of reward seeking, including feeding, could be overstimulated. This particular hyperactivation could explain the atypical feeding behaviors evidenced among ADHD patients (Cortese, Bernardina, & Mouren, 2007) and could play a role in the excessive motor activity used to self-promote wakefulness (Weinberg & Harper, 1993).

Patients with ADHD may also present with obesity as showed in several studies (Hanc & Cortese, 2018) underlying the possibility of a dysfunction in the hypocretin/orexin system. It is certainly common for children presenting with narcolepsy to have a weight increase in the first few years of hypersomnolence. Attention should be paid to this clinically when narcolepsy is diagnosed, however, there are little data to support the success of interventions for this in this population. There is some evidence to support aberrant food choices in children with narcolepsy resulting in increased caloric intake (van Holst et al., 2016). Moreover, sleep disturbances are known to imbalance hormone levels and to alter appetite regulation. Although patients with ADHD may be at increased risk for bulimia nervosa, as reported in a meta-analysis showing a similar level of risk for anorexia nervosa and binge eating disorders (Nazar et al., 2016), few studies have explored the characteristics of eating behaviors in patients with ADHD and in particular food and caloric intake prior, during or after treatment with psychostimulants.

Pubertal development is also a major issue when treating patients with narcolepsy, given the risk of advanced puberty associated with the disease (Poli et al., 2013). Advanced puberty has not been systematically reported among patients with ADHD. However, the hypocretin/orexin system seems to play an important role in growth and pubertal development by activating GnRH neurons involved in precocious puberty (Tao, Sharif, Zeng, Cai, & Guo, 2015). It is a notion to consider for future treatments given that psychostimulants used both in ADHD and narcolepsy may alter growth velocity (Poulton, Bui, Melzer, & Evans, 2016). Preliminary support for the hypocretin/orexin hypothesis was found in a pilot study of Mazindol (a direct orexin-2 receptor agonist) in children with ADHD (Konofal et al., 2014). This study showed that Mazindol was associated with improved ADHD symptoms (greater than 90% improvement from baseline) in 24 children aged 9–12 with ADHD (Konofal et al., 2014).

In summary, although the prevalence of narcolepsy in children with ADHD is unclear, it is well-accepted that children with ADHD experience higher levels of hypersomnolence compared to children without the disorder. Children with narcolepsy also have elevated levels of inattention, hyperactivity, and impulsivity symptoms. There are a number of theories connecting ADHD to excessive daytime sleepiness. It has been proposed that hyperactivity may develop as a strategy for patients with ADHD to increase their alertness. Dysfunction in the orexin system may also explain the overlap between these two conditions.

Sleep-related breathing disorders encompass a broad range of respiratory disorders that involve abnormal respiration during sleep. These disorders can affect all children across the developmental spectrum. Classification of sleep breathing disorders depends on the classification system being used. The DSM-5 outlines a number of sleep breathing disorders including Obstructive Sleep Apnea Hypopnea, Central Sleep Apnea, and Sleep-Related Hypoventilation (American Psychiatric Association, 2013). The International Classification of Sleep Disorders—3rd Edition outlines the criteria for Pediatric Obstructive Sleep Apnea (American Academy of Sleep Medicine, 2014). Sleep-related hypoventilation occurs with respiratory failure and central sleep apnea may be inherited such as with congenital disorders of hypoventilation (usually diagnosed in infancy—autosomal dominant) but may present as acquired with hypersomnolence and raised carbon dioxide levels in sleep.

This chapter will focus specifically on Obstructive Sleep Apnea Hypopnea, referred to as Obstructive Sleep Apnea (OSA) subsequently, given that this is the most common breathing disorder and has been the focus in ADHD research. OSA involves repeated episodes of upper (pharyngeal) airway obstruction during sleep (American Psychiatric Association, 2013). Moderate to severe OSA is associated with daytime sleepiness in more than half of cases (American Psychiatric Association, 2013). Challenges arise with definitions of numbers of events between adult and pediatric criteria and what constitutes mild, moderate, and severe, which have been arbitrarily constituted. In general, severity of OSA is defined by Obstructive Apnea Hypopnea Index (OAHI) with greater than 2 events/hour meeting criteria for OSA arbitrarily. Between 2 and 5 events/hour is generally described as mild, 5–10 events/hour as moderate, and greater than 10 events/hour as severe. However, many children display increased effort and decreased flow intermittently (upper airway resistance) throughout the night and the effects of moderate/mild and increased upper airway resistance on daytime function is largely unknown. Most research with respect to daytime effects has been focused on OAHI and saturation, however, it is not known whether other aspects of disrupted sleep such as arousals, fragmentation, and efficiency may have more impact and recent recommendations have suggested that arousal-based scoring should be included in the American Academy of Sleep Medicine criteria for the disorder (Malhotra et al., 2018).

In the general population, OSA affects about 1%–5% of children (Mindell & Owens, 2015). The prevalence appears to differ depending on whether it is assessed by parent report of symptoms (4%–11%) or more objective measures like PSG (range between 0.1% and 13%, 2% and 3% using strict OAHI>5—adult criteria) (Mindell & Owens, 2015). Primary snoring affects approximately 11% of children but again prevalence varies depending on the definition used (Mindell & Owens, 2015).

As described earlier in this chapter, the seminal meta-analysis by Cortese et al. (2009) found objective evidence of risk for OSA in children with ADHD compared to children without ADHD including higher parent-reported higher levels of sleep-disordered breathing (SDB) and a had higher AHI (indicative of sleep apnea) assessed objectively compared to non-ADHD controls. A more recent meta-analysis comprising 1113 children in the clinical group (874 with SDB assessed for ADHD; 239 with ADHD assessed for SDB) and 1405 controls found a moderate association between SDB and ADHD symptoms (Hedges’ g=0.57, P<.001) (Sedky, Bennett, & Carvalho, 2014). Primary snoring is also elevated in children with ADHD, affecting approximately 30% compared to 11% of children attending psychiatric and general pediatric clinics, respectively (Chervin, Dillon, Bassetti, Ganoczy, & Pituch, 1997). Furthermore, a study using overnight PSG found that up to 50% of children with ADHD had signs of SDB compared to 22% of children without ADHD (Golan et al., 2004).

Studies considering ADHD symptoms dimensionally have also found similar findings. In one large cross-sectional population-based study of 1114 adolescents (13–16 years), SDB (6% prevalence occurring weekly) was associated with more than two times the risk of the ADHD inattentive presentation when accounting for confounding variables including sociodemographic characteristics, mental health symptoms, medication use, and electronic media use (Johnson & Roth, 2006). Studies of OSA samples also show increased rates of ADHD, when ADHD is assessed both dimensionally (Precenzano et al., 2016) and categorically (Wu et al., 2017). For example, one retrospective study of children with OSA reported that 30% also met criteria for ADHD (Wu et al., 2017).

OSA results from an anatomically or functionally narrowed upper airway, usually including (Mindell & Owens, 2015):

Related posts:

Epidemiology and Etiology of Behavioral Insomnias, Circadian Rhythm Disorders, and Parasomnias in ADHD Child and Family Impacts of Sleep Problems in Children and Adolescents With ADHD Future Research Directions in Attention Deficit Hyperactivity Disorder and Sleep Assessing Sleep Problems in ADHD New Frontiers: Neurobiology of Sleep in ADHD Healthy Sleep Practices (Sleep Hygiene) in Children With ADHD

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