ADHD is characterized by impairing levels of inattention, hyperactivity, and/or impulsivity symptoms, which make aspects of school life harder for children including learning in the classroom (Faraone et al., 2015). Students with ADHD often have trouble paying attention, staying on task, being organized and behaving appropriately in the classroom (Langberg, Dvorsky, Marshall, & Evans, 2013). Underlying these behaviors is the child’s executive functioning skills, which include attention, planning, working memory, processing, vigilance, and the ability to shift between tasks. ADHD has been consistently associated with moderate deficits in executive functioning (Willcutt et al., 2005). Insufficient sleep can increase daytime sleepiness, impairing a student’s ability to concentrate and attend to school work; memory, and task processing speed may also decline (Frenda & Fenn, 2016). However, it remains uncertain if sleep problems have an independent and cumulative impact on cognition over and above the impact of ADHD (Kirov & Brand, 2014).

In the general population, sleep restriction studies have provided strong evidence that sleep plays an important role in cognitive functioning and that even moderate deprivation of 1 hour can impact attention, memory, and emotional control (Lim & Dinges, 2010). Reduced sleep over short periods in children can increase irritability and moodiness, as well as off-task behavior (Baum et al., 2014; Beebe, Field, Milller, Miller, & LeBlond, 2017; Gruber, Cassoff, Frenette, Wiebe, & Carrier, 2012). Alertness and vigilance seem to be most consistently affected by sleep deprivation, particularly in relation to less complex tasks. A meta-analysis examining the effects of sleep deprivation across a range of cognitive tasks (simple attention, complex attention, working memory, processing speed, short-term memory, and reasoning) found simple attention tasks are more susceptible to the effects of sleep deprivation than more complex tasks (Lim & Dinges, 2010). The cognitive declines associated with sleep deprivation were able to be reversed when normal sleep patterns were resumed.

Less is known about the effects of sleep deprivation on school-age children with ADHD. A sleep restriction study in a small sample of school-age children (mean age=8.7, SD=1.3; age range 7–11 years) with ADHD (n=11) and without ADHD (n=32) found restricted sleep was associated with poorer sustained attention in both groups and decreased accuracy (rates of errors of omission) in children with ADHD compared to their baseline scores (Gruber et al., 2011). These findings show that reduced sleep is likely to result in a cognitive decline for all children but may be associated with a bigger decline in functioning for children with ADHD.

Night-time sleep problems including insufficient and poor quality sleep have been linked to poorer cognitive functioning in school-age children in the broader population, including poor working memory (Steenari et al., 2003), reduced processing speed and inattention (Araújo & Almondes, 2014; Astill, Van der Heijden, Van Ijzendoorn, & Van Someren, 2012). However, only a small number of cross-sectional studies have examined the relation between sleep problems and aspects of cognitive functioning in school-age children with ADHD with mixed findings. For example, working memory deficits, as measured by a simple backwards digit span test, were associated with child reported total sleep problems in 5–13-year-old children with ADHD (N=189) (Sciberras, DePetro, Mensah, & Hiscock, 2015). In a clinical study of 37 male children with ADHD (age range 7–12 years), fragmented sleep and wake after sleep onset, evaluated by actigraphy, were associated with aspects of selective attention including greater error rates and lower response speeds (Lee et al., 2014). In contrast, a study in younger children (N=64; mean age 5.52; age range 4–7 years), with and without ADHD, found group differences in cognitive performance was best explained by symptoms of inattention. The authors concluded that ADHD symptoms rather than sleep may be the strongest contributor to problems with executive functioning (Schneider, Lam, & Mahone, 2016).

A study comparing the performance of students aged 7–18 years with ADHD and no sleep problems (n=52), sleep problems only (n=36), and both sleep problems and ADHD (n=32) across a range of cognitive tests found that students with ADHD and sleep problems (defined by self-report of sleep problems) exhibited a distinct cognitive profile in comparison to the other two groups (Sawyer et al., 2009). Children with both ADHD and sleep problems were likely to have more difficulty maintaining concentration and focus on learning tasks in comparison to children with either sleep problems or ADHD only as these students were more easily distracted by external stimuli in comparison to the other groups. There was no evidence that sleep problems provided a cumulative effect on cognitive deficits associated with ADHD on inattention, impulsivity, working memory or processing speed.

While these cross-sectional studies provide some insights into the relationship between sleep problems and cognition, it remains relatively unclear the extent to which sleep problems in school children with ADHD impact cognitive functions that are involved in every day learning over and above the impaired functioning that may result from ADHD alone. In addition, the large number of methodological differences between studies (e.g., actigraphy vs parent-reported sleep problems) make it difficult to consolidate results and to be conclusive about findings. However, they help to shape future research (Kirov & Brand, 2014) (see Chapter 14).

Sleep also plays an important role in the integration and consolidation of memories including consolidation of new learning and information into stable long-term memories both declarative (knowledge and information) and procedural (skills) (Ashworth, Hill, Karmiloff-Smith, & Dimitriou, 2014). Disrupted and shortened sleep may impact on these important functions and there is preliminary evidence that there may be differences in the memory consolidation process between children with and without ADHD (see Chapter 11).

Prior research indicates that most children with ADHD do worse on all indicators of academic achievement in comparison to non-ADHD peers. Academic achievement (or performance) is measured across a range of indicators including academic tests and teacher grades, grade point average (GPA) and parent and self-ratings of academic skills and competencies in academic domains (e.g., numeracy and literacy) (Langberg et al., 2013; Loe & Feldman, 2007; Zendarski et al., 2017a). Achievement at school may also be assessed on a range of non-academic outcomes including student behavior and student engagement. Indicators may include a student’s feelings of belonging and connectedness with school, as well as indicators such as absenteeism, lateness, and rates of suspension (Loe & Feldman, 2007; Zendarski, Sciberras, Mensah, & Hiscock, 2017b). While it is unequivocal that ADHD has a negative impact on academic achievement, somewhat less is known about the possible additional impact of sleep problems. In this section, the impact of broad sleep problems and daytime sleepiness are examined in relation to academic achievement in students with ADHD.

Sleep restriction studies have demonstrated that inadequate sleep can impact on behavior and classroom functioning in typical student groups (Beebe, 2011). Sleep-deprived students look and feel sleepier during the day and fall asleep more easily than students not deprived of sleep. As discussed, there is some evidence that shortened sleep may compromise cognitive functioning by impeding alertness, attention, memory, and reasoning. More complex tasks such as planning and decision-making may be less sensitive to sleep deprivation (Alhola & Polo-Kantola, 2007; Beebe, 2011). For example, in one experimental study, 87 healthy adolescents (aged 10.0–16.9 years) underwent a 3-week sleep manipulation protocol using a cross-over randomized design (Beebe et al., 2017). Participants were randomized to either shortened sleep (6.5 hours in bed) or healthy sleep (10 hours in bed) across two 5-night periods. Classroom achievement tasks were measured in a simulated classroom each morning. On average, participants in the shortened sleep group slept 6.5 hours and those in the healthy sleep group slept 9.1 hours. Adolescents reported being sleepier and less attentive during the day when sleep was restricted and had lower scores on classroom tests in comparison to when they obtained healthy sleep, although effect sizes were modest (Beebe et al., 2017). Sleep restriction studies with academic function as an outcome, are yet to be replicated in ADHD samples and it remains unknown if shortened sleep induces significant daytime sleepiness and impaired classroom performance in students with ADHD. It is also not clear whether these findings in artificial classroom settings would be replicated in real life.

While findings regarding the impact of sleep on academic achievement in the general student population have been mixed, a meta-analysis of 86 studies reported a weak positive relationship between sleep duration and academic achievement (r=.09, CI 0.06, 0.12) in typical school students aged 5–12 years (Astill et al., 2012). There is a paucity of research that explicitly examines the relationship between sleep and academic performance for children and adolescents with ADHD. The two studies in students with ADHD did not find evidence of a relationship between sleep duration and academic outcomes for adolescents with ADHD when taking into account ADHD symptoms (Langberg et al., 2013; Zendarski et al., 2017a). Langberg, Dvorsky, Becker, and Molitor (2014) investigated the relationship between academic achievement and sleep in 100 middle school students with ADHD (mean age 11.9 years). Results showed self-reported sleep duration was not significantly associated with academic outcomes including student GPA, homework problems or teacher-reported academic competency. Similarly, another recent study examining the academic achievement of 130 high school students (mean age 13.7 years) found no significant association between parent-reported sleep problems (none/mild versus moderate/severe) and standardized tests of literacy and numeracy (Zendarski et al., 2017a). Current research suggests that sleep may not be a strong contributor to academic difficulties experienced by students with ADHD, most likely because ADHD itself, as well as IQ and comorbid learning difficulties, are strongly associated with academic achievement (Loe & Feldman, 2007).

In this section, we consider the relationship between sleep and social–emotional functioning in children with ADHD. The term “social–emotional” functioning is purposefully broad and includes dimensional measures of social and emotional functioning (e.g., internalizing and externalizing symptoms), as well categorical measures including the presence or absence of a diagnostic disorder. The term is also used to capture general well-being including quality of life. It is well-recognized that sleep is central to healthy social–emotional functioning and well-being in children. Sleep problems may contribute to the development of anxiety, depression, or externalizing behavioral problems (Alfano & Gamble, 2009; Kamphuis, Meerlo, Koolhaas, & Lancel, 2012), poor emotional control, problems with daily functioning and reduced quality of life (Kahn, Sheppes, & Sadeh, 2013; Sung et al., 2008).

Sleep restriction studies show that there is a range of psychological consequences related to not getting enough sleep including increased internalizing and externalizing problems, as well as decreasing the ability of children to adapt and respond appropriately to challenging contexts. One study (Baum et al., 2014) examined the impact of sleep on mood in a sample of adolescents (N=40, age range 14–17 years). Adolescents were randomized to either a restricted sleep (6.5 hours in bed) or healthy sleep duration (10 hours in bed per night) over a school week (5 nights). Both parents and adolescents in the restricted sleep group reported more oppositional/irritable symptoms, as well as poorer emotional control in comparison to participants in the healthy sleep group.

Many children with ADHD already have a range of comorbid behavioral difficulties including oppositional and defiant behavior and aggression, are more irritable and have poorer self-regulation and emotional control in comparison to same-aged children. Comorbid conditions are common (>60%) including both internalizing (i.e., anxiety and depression) and externalizing disorders (i.e., oppositional defiant disorder and conduct disorder), as well as other comorbidities including Autism Spectrum Disorders, learning disorders and sluggish cognitive tempo (Becker et al., 2016; Smalley et al., 2007; Spencer, 2006). Importantly, the specific type of comorbid issue may have different associations with various sleep problems. Becker, Cusick, Sidol, Epstein, and Tamm (2018) recently examined how anxiety, depressive, oppositional, inattentive, and hyperactive symptoms were differentially associated with a number of sleep problems in children with ADHD (n=181; age range 7–13 years). Anxiety was uniquely associated with greater bedtime resistance and sleep anxiety, depressive symptoms were associated with increased daytime sleepiness, both depressive and oppositional symptoms were associated with shorter sleep duration, and hyperactive symptoms were associated with increased night wakings and parasomnias. Only depressive symptoms were independently associated with total sleep problems. This highlights an important limitation in the field; the majority of studies have used an overall measure of sleep problems rather than examining whether specific sleep domains are associated with child functioning.

A number of studies have examined the link between sleep problems and co-occurring internalizing and externalizing comorbidities in children with ADHD (Accardo et al., 2012; Becker, Langberg, & Evans, 2015b; Becker et al., 2016; Gregory & Sadeh, 2012; Lycett, Sciberras, Mensah, & Hiscock, 2015). Lycett et al. (2015) found that children with ADHD and either externalizing or internalizing comorbidities are twice as likely to experience moderate to severe sleep problems in comparison to children without these difficulties, and children with both comorbid conditions are three times as likely to experience sleep problems. However, specific internalizing and externalizing comorbidities have been inconsistently linked with sleep problems. For example, anxiety has been linked to increased sleep problems in children with ADHD (Accardo et al., 2012), while in another study sleep problems did not prospectively predict increases in anxiety (Becker et al., 2015b) in children with ADHD. In a sample of young adolescents (ages 10–14 years) diagnosed with ADHD, parent-reported sleep problems were associated with increases in depressive symptoms and externalizing symptoms 1 year later, even after accounting for baseline symptoms (Becker et al., 2015b). In a subsequent study examining sleep problems in relation to comorbidity in children (6–11 years) with ADHD inattentive presentation (ADHD-I), comorbid anxiety but not oppositional behavior or depression was associated with sleep problems (Becker et al., 2016).

Most of the research investigating the association between sleep problems and externalizing or internalizing comorbidities in children with ADHD is cross-sectional or only investigates sleep problems over a relatively short period of time (i.e., 12 months). This limits our ability to draw conclusions about the causal pathways, direction of relationships and our understanding of the developmental course of sleep problems from childhood to adolescence in children with ADHD. It likely that the relationships are multifaceted and bidirectional and may be related in some part to overlapping neurodevelopmental processes (Dorris, Scott, Zuberi, Gibson, & Espie, 2008; Kahn et al., 2013; Moreau, Rouleau, & Morin, 2014).

Two recent studies have sought to examine the bidirectional relationship between sleep and internalizing and externalizing symptoms in school-age children. One in typically developing children (Quach, Nguyen, Williams, & Sciberras, 2017) and the other in a clinical sample of school children diagnosed with ADHD (Mulraney, Giallo, Lycett, Mensah, & Sciberras, 2016). In both these studies, behavioral outcomes were measured on subscales of the Strengths and Difficulties Questionnaire (SDQ), a well-validated screening measure for child and adolescent problem behaviors (Goodman, 2001). Both studies examined internalizing (i.e., emotional problems) and externalizing symptoms (i.e., conduct problems) on SDQ subscales. Understanding the nature of these interrelationships is important to help determine when to intervene and what areas to target.

Quach et al. (2017) examined sleep and behavioral problems in a nationally representative sample of Australian children (N=4983; 79% retention) followed biennially from kindergarten (4–5 years) to early adolescence (12–13 years). Sleep problems in early childhood predicted later behavioral problems on both internalizing and externalizing dimensions and externalizing, but not internalizing, symptoms predicted later sleep problems. Findings suggest that treating sleep problems in the early school years may decrease later internalizing and externalizing problems, and interventions focused on decreasing externalizing symptoms will likely improve sleep. Mulraney et al. (2016) examined this same bidirectional relationship in school-age children aged 5–13 years with ADHD (N=270) across 3-time points over a 12-month period. There was a reciprocal, though weak, relationship between sleep problems and internalizing symptoms, and no evidence of a reciprocal relationship between externalizing symptoms and sleep problems. It is likely that the inconsistent findings are related to different methodology. Mulraney et al. only followed their ADHD sample for 12 months. Further, Quach et al. examined a large nationally representative sample of children whilst Mulraney et al. followed a clinical sample of children with ADHD.

Family environments play a pivotal role in child development and family plays an important role in shaping young people’s behaviors, beliefs, and values. In relation to sleep, parent attitudes toward sleep and sleep behaviors, as well as attitudes towards child sleep are likely to influence child sleep habits (Meltzer & Montgomery-Downs, 2011). The reverse is also true, where child sleep problems can impact on parent depression, family function and marital conflict (El-Sheikh, Buckhalt, Mize, & Acebo, 2006). Family socioeconomic disadvantage has also been associated with increased sleep problems in school-age children. A recent review examining the interconnection between child sleep and aspects of family functioning in community samples of children found children’s sleep problems can disrupt family functioning and parent sleep leading to increased parent stress, higher marital conflict and less family cohesion. Sleep is not only a predictor of poor family functioning, but poor family functioning may also have reciprocal effects on child sleep habits (El-Sheikh & Kelly, 2017).

Parenting a child with ADHD is often associated with more parenting stress in comparison to parenting typically developing children (Craig et al., 2016). Parenting stress has been associated with ADHD symptom severity, parenting children with more challenging behaviors, and higher parental conflict (Theule et al., 2013). Parenting children with sleep problems may also contribute to increased parent stress (Meltzer & Montgomery-Downs, 2011), and this finding has been replicated for children with ADHD (Sung et al., 2008). Sung et al. (2008) highlighted for the first time that sleep problems in children with ADHD (mean age 11.7, age range 5–18 years) were associated with poor family outcomes in comparison to children with ADHD and no sleep problems. Poorer caregiver mental health and work attendance and poorer family quality of life were observed in families of children with moderate to severe behavioral sleep problems. Similarly, Lycett et al. (2016) found both transient and persistent sleep problems in children with ADHD were associated with poorer family quality of life and reduced family wellbeing including poorer parent mental health and increased primary-caregiver work difficulties (i.e., arriving late). Overall, these findings suggest that moderate to severe sleep problems in children with ADHD can increase caregiver burden and reduce quality of life for families of children with ADHD.

Parenting also plays a key role in shaping a child’s sleep habits (El-Sheikh & Kelly, 2017). In a sample of school-age children with ADHD (n=361), consistent parenting and good sleep hygiene have been associated with fewer behavioral sleep problems (Sciberras, Song, Mulraney, Schuster, & Hiscock, 2017). Specifically, this study found consistent parenting was associated with decreased bedtime resistance and sleep anxiety, while poor sleep hygiene was associated with increased bedtime resistance, shorter sleep duration, and daytime sleepiness. Establishing consistent bedtime routines may help prevent child sleep difficulties especially relating to bedtime resistance (Noble, O’Laughlin, & Brubaker, 2011).

In addition, parental monitoring and rules (i.e., established bedtimes) have been associated with lower adolescent psychological distress and greater sleep efficiency in typically developing adolescents, suggesting good family functioning may play a protective role in regard to adolescent sleep (Bernert, Merrill, Braithwaite, Van Orden, & Joiner, 2007). Poor family supervision and monitoring during early adolescence in students with ADHD have also been associated with lower student engagement (Zendarski et al., 2017b) and poor reading achievement in Australian high school students with ADHD (Zendarski et al., 2017a). Evidence suggests that because ADHD tends to cluster in families (genetic link), children with ADHD are more likely to have parents who also exhibit symptoms such as disorganization and inattentiveness. This likely influences parenting practices and family functioning and consequently impacts upon the family’s ability to set consistent limits around sleep. For example, there is a relationship between high levels of ADHD symptoms in mothers and poor parenting behaviors including less involved parenting, lower positive parenting, and inconsistent use of discipline (Chronis-Tuscano et al., 2011).