The Unappreciated Role of Sleep in ADHD: An Examination of Sleep and Its Role in ADHD Symptomology
The Unappreciated Role of Sleep in ADHD: An Examination of Sleep and Its Role in ADHD Symptomology
Every good day starts and ends with a good night’s sleep. During sleep our bodies and minds rest and recharge, we unconsciously reflect on the things that happened throughout our day, and consolidate new information about the world around us. Sleep is important for our survival and falls closely to our needs for food, water, and shelter. When it comes to the importance of sleep in children and adolescents, it plays a crucial role in development, having a tremendous impact on not only the physical growth and development of children and adolescents, but also on their neurobehavioral and cognitive health. When it comes to the importance of sleep in our development, it is no wonder why sleep disorders and disturbances in childhood are taken so seriously. Despite many DSM-5-TR disorders having identified sleep problems as either a diagnostic feature or as a comorbid disorder, when it comes to attention-deficit/hyperactivity disorder (ADHD), arguably the most predominant neurodevelopmental disorder to affect children and adolescents, the impact sleep-disturbances play within ADHD’s etiology goes beyond just feeling a little tired. For those of you who have made it this far join me as I dive deeper into the unspoken impact sleep problems have on ADHD symptomology, examining primary sleep disturbances as part of the pathophysiology of ADHD in children and adolescents, via a brief examination of some of the current findings on the relationship between sleep and ADHD.
What is Attention Deficit Hyperactivity Disorder?
Considered to be one of the most commonly diagnosed neurodevelopmental disorders in children and adolescents, Attention-deficit/hyperactivity disorder (ADHD) is a clinical diagnosis characterized by symptoms of developmentally inappropriate inattention and/or hyperactivity-impulsivity that significantly impair an individual’s day-to-day functioning (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision [DSM-5], 2022). ADHD has an onset in early childhood, before the age of 12 years, causing impairments in functioning across two or more settings, affecting an estimated 5-9% of children and adolescents and 2.5-5% of adults worldwide (Canadian ADHD Resource Alliance [CADDRA], 2024; Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition [DSM-5], 2022). Of those diagnosed in childhood and adolescence, approximately 50% of them will continue to experience symptoms throughout their adult life (CADDRA, 2024). Generally speaking, ADHD is a psychiatric disorder that involves deficits in executive functioning. Executive functioning refers to the cognitive processes within the brain that activate, integrate, and govern other brain functions, and underlies one’s ability to self-regulate behaviour (Mash & Wolf, 2019). This includes capacity for self-awareness, self-evaluation, planning, and self-monitoring and vary from cognitive, language, motor, and emotional processes (Mash & Wolf, 2019). For example, some individuals with ADHD may display excessive amounts of daytime drowsiness and slowed information processing speeds, as well as increased levels of fatigue; these are reflective of executive functioning impairments in an individual’s ability to regulate their levels of alertness and processing speed (Mash & Wolfe, 2019). ADHD impacts multiple areas of a child’s life, impairing their social and academic functioning, and if left undiagnosed or untreated can further impair their occupational functioning as adults, and predispose them to an array of other psychiatric and social disorders later in life.
Understanding Sleep: The Basics
To say that sleep is important is an understatement. As a basic human need for survival, sleep plays a vital role in both our mental and physical health, and is influenced by both the amount and quality of sleep we receive each night. The human body naturally follows a 24-hour cycle that helps our bodies identify when it is time to sleep known as our ‘circadian rhythm’ (APA, 2018). It is common knowledge that sleep helps our brain function properly, and that not getting enough sleep or experiencing a poor quality of sleep, either acutely or chronically, has its consequences. The most obvious side effects of lack of or poor quality of sleep include fatigue (both mental and physical), increased yawning, difficulties focusing, and increased feelings of irritability or ‘crankiness’(APA, 2018; Wajszilber, Santiseban, & Gruber, 2018). An individual’s ability to regulate mood and make decisions can also be impacted (APA, 2018). Although the amount of sleep a person requires generally varies from person to person, and varies depending on age, the National Sleep Foundation (2019) recommends that school aged children (6-13 years) receive 9-11 hours of sleep per night, and that adolescents (14-17 years) ideally aim for an average of 8-10 hours of sleep per night. Unfortunately, recent research from the National Sleep Foundation (2019) suggests that many individuals do not receive enough sleep, with close to 30% of adults receiving less than six hours of sleep each night and 30% of teens receiving an average of eight hours of sleep per school night. Multiple studies have consistently found that when the amount of sleep for participants is limited to below the suggested average for that age group, participant’s cognitive abilities significantly decrease and their abilities to regulate their mood/emotions become noticeably impaired (Arns & Vollebregt, 2018; Dan, Asraf, Cohen, & Haimov, 2017; Millman, 2005). Of these studies some of them also looked at sleep deprivation and its impact on cognitive functioning in participants with a clinical ADHD diagnosis. Their findings found that sleep deprivation ultimately worsens the already impaired cognitive abilities of ADHD patients – exacerbating their symptoms of inattentiveness, impulsivity, mood/emotional dysregulation, daytime sleepiness/fatigue and, in some cases, also resulted in worsening symptoms of hyperactivity including increased levels of talkativeness and inappropriate movements, further illustrating the importance of sleep on basic cognitive functioning and emotional regulation (Arns & Vollebregt, 2018; Dan et al., 2017). Knowing how important sleep is to the average person’s health, it is no wonder why sleep-wake disorders are taken so seriously by physicians and clinicians, especially when presented in children and adolescents.
Sleep-Wake Disorders: What You Need to Know
Sleep-wake disorders are a DSM-5-TR classification of disorders involving difficulties with the timing, amount, and quality of sleep a person receives resulting in various problems with regards to an individual’s day-to-day functioning and their sense of distress (APA, 2018; DSM-5-TR, 2022). The DSM-5-TR (2022) identifies 10 sleep-wake disorders or disorder groups: insomnia disorder, hypersomnolence disorder, narcolepsy, breathing related disorders, circadian rhythm sleep-wake disorders (CRSDs), non-rapid eye movement (NREM) sleep arousal disorders, nightmare disorder, rapid eye movement (REM) sleep behaviour disorder, restless leg syndrome (RLS), and substance/medication-induced sleep disorder. Individuals with a sleep-wake disorder, more commonly referred to in the majority of research as a sleep disorder, typically present with complaints of sleep-wake dissatisfaction regarding the timing, amount, and quality of their sleep (APA, 2018). This results in increased daytime distress and impairments across multiple areas of functioning (DSM-5-TR, 2022). Many DSM-5-TR disorders have acknowledged sleep difficulties as a diagnostic feature or as an inferred comorbidity, and yet the interplay between sleep disorders and ADHD remains inadequately discussed (Arns & Vollebregt, 2018).
Sleep-Wake Disorders and ADHD Symptomology: How Are They Related?
Sleep disturbances are reported in approximately 25-50% of children and adolescents diagnosed with ADHD (Gruber, 2018; Ivanenko, A. Lurie, & R. Lurie, 2016). The most commonly seen sleep related disturbances in children and adolescents include behavioural problems such as bedtime resistance or refusal and inconsistent bedtime/sleep routines, as well as, delayed sleep-onset associated with delayed melatonin synthesis onset, sleep-onset insomnia, dyssomnia and parasomnia, breathing-related sleep disorders (e.g. obstructive sleep apnea-hypopnea, central sleep apnea), and RLS (Gruber, 2018; Ivanenko et al., 2016; Ricketts et al., 2018; Wajszilber et al., 2018). Studies have consistently found that sleep in children with ADHD tends to be more restless and agitated, with many children experiencing greater difficulties initiating and maintaining sleep, as well as experiencing more night-wakings and prolonged sleep latencies (Hoosier, Gregory, Paasch, Ewen, & Lam, 2018; Lecendreux, Konofal, Bouvard, Falissard, & Mouren-Siméoni, 2000). Lab studies investigating the interplay between sleep and ADHD have found that the presence of sleep difficulties and sleep disorders in ADHD is suggestive of a possible link between an “intrinsic” dysregulation of sleep/wakefulness and ADHD-related central nervous system (CNS) dysfunctions (Owens, 2008; Wajszilber et al., 2018). There is substantial empirical evidence demonstrating an overlap in the centers of the CNS regulating sleep and attention/arousal. Disruptions within one of these systems ultimately results in a parallel effect on the other (Owens, 2008; Wajszilber et al., 2018). Additionally, both ADHD and sleep disorders have identified similarities including disruptions in neurotransmitter pathways, particularly in dopaminergic (eg. substantia nigra) systems (Owens, 2008; Wajszilber et al., 2018). There is a large volume of research suggesting that ADHD and sleep disturbances are the result of an underlying central nervous system pathology involving associative integrative functions and the brain’s prefrontal cortex (Owens, 2008). Despite the frequency with which parents and patients report sleep disturbances in ADHD, and the substantial empirical evidence supporting various biological links between sleep problems and the disorder, no mention of sleep or sleep behaviours are made within the DSM-5 diagnostic criteria for ADHD (Lecendreux et al., 2000; Owens, 2008). No sleep-wake disorders or other sleep disturbances are mentioned within the DSM-5 as possible comorbidities or differential diagnosis for ADHD under the disorder’s diagnostic criteria, however, ADHD is listed as a possible comorbidity for restless legs syndrome and as a possible differential diagnosis for obstructive sleep apnea hypopnea (DSM-5-TR, 2022, 2013). As mentioned, the link between sleep and ADHD is complicated and can present itself in multiple clinical guises. For example, the symptomology of obstructive sleep apnea-hypopnea (OSAH) may mimic those of ADHD. OSAH is a breathing-related sleep-wake disorder characterized by frequent and repeated episodes of interrupted breathing during sleep from either decreased airflow (hypopnea) or an absence of airflow (apnea; Olson, Moore, Morgenthaler, Gay, & Staats, 2003). These interrupted breathing patterns, caused by a collapse in the upper airways during sleep, can result in fragmented sleep, nocturnal breathing disturbances (e.g. snorting/gasping, snoring, or breathing pauses), and unrefreshing quality of sleep despite sufficient quantity and opportunity (DSM-5-TR, 2022). OSAH can also have significant cardiovascular and neurobehavioral consequences (DSM-5-TR, 2022; Olson et al., 2003). The neurobehavioral symptoms of OSAH mimic those of ADHD, and include daytime sleepiness, fatigue, mood/emotional dysregulation, impaired vigilance, and cognitive dysfunction (Olson et al., 2003). Neurodevelopmental disorders, including ADHD, are listed as a possible comorbidity under some of the circadian rhythm sleep-wake disorders (DSM-5-TR, 2022). Thus, while investigating a sleep-wake disorder, clinicians may be more inclined to look at the possibility of an ADHD diagnosis as opposed to investigating the possibility of a sleep-wake disorder when investigating an ADHD diagnosis.
Poor Sleep Quantity, Quality, and Aggravated ADHD Symptomology
One of the potential consequences of having a sleep disorder is suffering from sleep deprivation. Sleep deprivation can contribute to symptoms of inattentiveness, impulsivity, daytime sleepiness, fatigue, mood/emotional dysregulation, and, in some cases, increased hyperactivity (Wajszilber et al., 2018). Due to the striking similarities between symptoms, it is easy to see how a sleep disorder may be mistakenly diagnosed at first glance as ADHD and vice-versa. A comorbid sleep disorder or the presence of other sleep related difficulties may be overlooked, causing ADHD symptoms to be attributed to a more severe case of ADHD. Studies examining insufficient and poor-quality sleep in children and adolescents have consistently found that sleep deprivation and poor-quality of sleep often cause, and correlate with, increased levels of irritability, impulsivity, inattention, increased daytime fatigue/sleepiness, and increased difficulties with emotional/behavioural regulation (Dan et al., 2017; Gruber, 2018; Millman, 2005; Owens, 2008). These difficulties can negatively impact an individual’s academic/occupational performance and social functioning, decreasing their overall quality of life (Wajszilber et al., 2018). In non-ADHD adolescent cases, insufficient sleep and its side effects have been linked to other serious consequences including increased incidence of car accidents and crashes (Millman, 2005). In children and adolescents with ADHD, research has found that poor sleep quality and quantity further exacerbate ADHD symptoms of inattention, impulsivity, and mood/behavioural dysregulation (Gruber, 2018; Wajszilber et al., 2018). It was also found that in some ADHD cases poor sleep results in increased incidents of daytime sleepiness, while in other ADHD cases it lead to increased levels of hyperactivity (Arns & Vollebregt, 2018; Owens, 2008; Wajszilber et al., 2018). The results of many previous works investigating the characteristic symptom of hyperactivity in ADHD may be reflective of a compensatory response against fatigue, because the brains of individuals with ADHD are under-stimulated, causing fatigue and daytime sleepiness in some (Lecendreux et al., 2000). Excessive motor activity in ADHD patients may actually be a strategy their bodies use as a way of combating their “sleepy brains”, aiding them in staying awake and alert (Lecendreux et al., 2000; Wajszilber et al., 2018). If hyperactivity in ADHD patients is a biological strategy implemented by their bodies to help them stay awake and combat their under stimulated CNS, then the increased levels of hyperactivity in sleep deprived and comorbid sleep disorder ADHD cases would be reflective of their bodies’ increased need to fight and remain alert and wake. Thus, for patients with ADHD, the presence of a sleep disorder or other sleep difficulties resulting in insufficient or poor-quality sleep, may be more problematic as it has a direct effect on the severity of ADHD symptoms.
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Written by: Casie Chang, Registered Psychologist (Provisional) with Wildflowers
