ADHD & Snoring
What has ADHD got to do with snoring and sleep apnoea?
Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common childhood and adolescent behavioural disorders with an estimated prevalence of 5% in school age children. It is characterised by developmentally inappropriate symptoms of inattention and impulsivity, and impacts on daily functioning in health, mood, behaviour, academic performance and quality of life. Sleep complaints in children with ADHD have been reported in up to 55% of cases.
Around 25% of all children experience some type of sleep problem and around 12% present with snoring and sleep apnoea. This type of sleep disorder is also known as SDB (sleep disordered breathing). The interrelations of ADHD and sleep disorders such as snoring and sleep apnoea are complex with significant impact on a child's functioning. As symptoms and consequences tend to overlap these associations are often not recognised by parents and clinicians.
I thought it was only men who snore?
In adults, sleep apnoea is characterised by repetitive episodes of upper airway obstruction that occur during sleep giving rise to apnoeas (periods of not breathing for more than 10 seconds, followed by a reduction in the depth of sleep, which is termed an arousal). There is usually a lowering of blood oxygen saturation, loud snoring, witnessed breathing interruptions and arousal accompanied by gasping, choking, restlessness, sweating and often acid reflux and nocturia. This leads to many daytime symptoms such as excessive daytime sleepiness, poor health and cognitive impairment. Sleep apnoea is associated with significant co-morbidities such as cardiovascular, metabolic and neurocognitive complications as well as vehicle and occupational accidents. The prevalence of sleep apnoea is difficult to determine as many individuals are unaware that they have the condition and others may not come forward for diagnosis and treatment. Although it is well documented that men have a higher incidence of sleep apnoea than women (ratio 2:1) it can affect women and children of all ages. However, women and children often display symptoms that are not seen in men, for example, women will be more concerned about insomnia, morning headache, anxiety and depression than the snoring itself. Results from a large epidemiological study estimated that sleep apnoea was undiagnosed in more than 90% of women with moderate to severe sleep apnoea as their clinical presentation of symptoms differed from those of men. This is also the case with children as parents and clinicians are unaware of these differences.
Children are not mini adults
The aetiology of paediatric sleep disorders is complex as factors that are not seen in adults must be considered. In the case of snoring and sleep apnoea, small skeletal structure, craniofacial malformations, impaired neuromuscular tone, large lymphoid tissue (tonsils and adenoids which tend to decrease in size after around 8 years), impaired neural response and altered arousal threshold contribute to SDB. The growing obesity epidemic also contributes to the prevalence of sleep apnoea in older children and adolescents.
Children will display similar nocturnal symptoms to those of adults, but tend to adopt an abnormal sleeping position. A child will sleep on the knees with the neck hyperextended in order to breathe. In this position parents are unlikely to witness snoring and apnoeas. Children with sleep apnoea will have a 'long face' appearance with mouth breathing, chronic nasal congestion, hyponasal speech and daytime symptoms that mimic ADHD. Like adults, children with SDB have disrupted sleep due to frequent awakenings. Children with SDB are more likely to have nocturnal enuresis (due to hormone secretions related to disturbed sleep), growth failure that may be related to the metabolic needs from increased work of nocturnal breathing, and alterations in normal nocturnal growth hormone secretion.
What came first - SDB or ADHD?
It is important to make the distinction between the sleep problems of children with ADHD and those children whose initial problem is a sleep disturbance resulting in daytime ADHD like symptoms. Overall symptom severity has been found to be higher in children with ADHD as a consequence of their SDB than those with behavioural ADHD. It would be expected that daytime behaviour symptoms will improve following treatment for SDB.
Treat SDB and improve sleep and behaviour
Enlarged tonsils and adenoids are probably the most common cause of paediatric snoring and sleep apnoea in children under the age of 8 years. However, there are many reasons why children snore or have sleep apnoea and it is imperative that they are carefully screened to achieve the most appropriate treatment. That said, adenotonsillectomy is generally the treatment of choice for children with enlarged tonsils and adenoids. The overall success of this method is around 80% but for some children who have a familial history of snoring and sleep apnoea or those whose ethnicity pre-disposes to snoring, removing tonsils and adenoids may not be wholly successful. In adults, snoring and sleep apnoea are rarely functions of just one contributor but generally a collective problem. For example, multifactorial snoring is a function of both palatal flutter and tongue base vibration. It may also encompass a small narrow airway that is prone to collapse. In this instance each of these areas needs to be treated in order to stop snoring. Similarly with children, removal of the tonsils and adenoids may be a temporary measure but as the child matures into adulthood any familial traits of snoring may become apparent and will then need to be addressed accordingly.
The use of nasal steroids to reduce the volume of tonsil and adenoid tissue has been of interest. It has shown a reduction in the number of apnoeas but not complete cessation. It has been found from polysomnographic and symptom scores, that children with mild sleep apnoea had a substantial decrease in apnoea events following a 6 week treatment period of nasal steroids. These improvements lasted for several months after treatment. Although these studies concluded that the use of nasal steroids as a therapeutic option is fully justified they have not addressed the long term treatment needs of these children with sleep apnoea.
Sleep apnoea due to craniofacial or jaw joint disorders is generally a familial trait that is best resolved at an early age. In the case of craniofacial abnormalities it is easier to correct during childhood and can be resolved with the use of oral appliances. Oral appliances improve upper airway patency during sleep by enlarging the upper airway and/or decreasing upper airway collapsibility and enhancing upper airway muscle tone. These appliances have been found to resolve apnoea symptoms and the devices are well tolerated by most children.
CPAP (Continuous Positive Airway Pressure) is a small machine that blows room air at a positive pressure into the airway to prevent snoring and apnoea. It is generally the first line of treatment for adults with OSA. However, due to its low attractiveness CPAP is generally reserved for moderate to severe cases of sleep apnoea in children. Despite this it is an efficient method of treatment with very few side effects. Research has consistently found that those children who can tolerate oral appliances or CPAP have considerably improved symptoms of both OSA and ADHD with their use.
Drug treatments adversely affect sleep
There has been increasing interest in treating children with ADHD with stimulants and other approved and non-approved drugs. However, they are all likely to affect sleep due to their mechanism of action. The use of amphetamine and other stimulants such as Ritalin (Methylphenidate), is associated with shortened sleep duration and Rapid Eye Movement or REM suppression. Maximum plasma concentration occurs after about 2 hours of oral ingestion but this is variable between individuals. Ritalin is a short acting stimulant with an action of between 1 and 4 hours and a half-life of 2-3 hours in the immediate release preparations. This means that several doses are required throughout the day. The consequences of these drugs can be overcome by adjusting the dose, timing or formulation. Sleep disturbance can be improved by prescribing a shorter acting preparation. Disturbed sleep whether drug induced or not, can have a devastating effect on a child's physical and mental development.
Can Melatonin help or hinder?
Melatonin if given 2 hours before bedtime can induce sleep onset and is useful for chronic insomnia. There has been research into the administration of melatonin along with Ritalin to increase sleep and reduce ADHD symptoms. However, this regime partially improved symptoms of sleep disturbance but did not reduce the attention deficit and hyperactivity behaviour of children with ADHD.
What does research tell us?
There has been much research linking sleep disorders and ADHD. Many researchers have found a strong correlation between children with snoring and sleep apnoea, and ADHD, whilst others found no significant correlation. Some studies have however found a significant improvement in children's behaviour following treatment for their snoring and sleep apnoea by adenotonsillectomy.
ADHD and other sleep disorders
Many studies have found children diagnosed with ADHD have significant differences in rates of night time symptoms compared with normal controls. Nightmares, bruxism, nocturnal enuresis, snoring and restless sleep are prominent in children with ADHD compared with normal children. For example, nocturnal bruxism was found in 43% of ADHD children compared with 17% in normal controls. Similarly, low academic performance was significantly higher at 6% in ADHD as opposed to only 1.8% of normal controls.
It has been found that children with ADHD have decreased REM sleep compared to normal children and there is a suggestion that children with ADHD have an abnormality in the regulation of sleep and arousal. Indeed, many of these children are reported to have difficulty getting to sleep. These sleep onset problems may reflect a physiological difficulty in falling asleep as opposed to a behavioural sleep onset problem. Sleep loss for as little as 3 nights in a row can significantly affect both day and night-time functioning and thus exacerbate an already serious condition. In this trial researchers did not look for any association between ADHD and sleep disordered breathing but acknowledged that they did not include polysomnography testing for SDB and therefore could not rule out the presence of SDB which is common in children with ADHD.
Better sleep hygiene
One interesting study investigated the link between poor sleep hygiene and problem daytime behaviours in snoring and non-snoring school age children. Poor sleep hygiene alone can substantially affect daily functioning in many areas including health, mood, behaviour regulation, academic performance and overall quality of life. The research found that snoring children were affected in all areas of daytime functioning far more than non-snoring children. The authors concluded that non-snoring children may not be as susceptible to the daytime effects of poor sleep hygiene as a child who snores and is already at risk for daytime behaviour problems.
Treat with medications or surgery?
However, another study investigating SDB in children diagnosed with ADHD found no more evidence of SDB in children diagnosed with ADHD than matched controls. This particular study was also investigating whether Ritalin medication had any effect on breathing variables as sleep problems in ADHD have been attributed to the use of stimulants. They found no effect on breathing although the authors acknowledged that treatment for SDB would improve ADHD symptomology without the need for stimulant medications. Indeed a further study concluded that children with ADHD and SDB improved significantly after adenotonsillectomy compared with those who received just stimulant treatment.
Clearly there is diversity within research about the link between SDB and ADHD. Children undergoing evaluation for ADHD should routinely be screened for sleep disorders. Treating sleep disorders can reduce or eliminate the daytime symptoms of ADHD and have considerable positive effects on quality of life. For those children who have ADHD without sleep disorders, it may be beneficial to investigate the relationship between sleep hygiene and problem behaviours. It is however still difficult to determine whether poor sleep practices elicit bad behaviour or whether bad behaviour elicits poor sleep.
At present there is a lack of evidence on the most effective and safe treatment strategies (both pharmacological and non-pharmacological). Behavioural strategies for sleep problems could be developed further especially in the area of sleep hygiene and bed time routines. CBT (Cognitive Behavioural Therapy) in adults with chronic insomnia is well underway and proving highly successful. A study with a similar intervention adapted for the needs of children might reap benefits.
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