Why is Sleep Important for Children - Part 24 (Growth Hormone Deficiency)
Sleep apnea is a common condition in adults, and it can also occur in children. What factors cause sleep apnea to occur in children?
Sleep apnea is a common condition in adults, and it can also occur in children. What factors cause sleep apnea to occur in children? There are various contributions that can lead to a narrowing or instability of the upper airway, which can cause the pauses in breathing characteristic of sleep apnea. As sleep apnea can have serious consequences in children including impacts on growth, intelligence, and behavior, it is important to identify correctable causes.
When sleep is disrupted in young children, especially those who have yet to finish growing, there can be significant consequences. Growth hormone is secreted during the night during specific sleep stages.
Deep, non-REM sleep that occurs early in the night seems especially important for its secretion. This sleep predominates in the first third of the night. If this sleep is disrupted, growth may not occur normally. Children who are affected may begin to fall off their growth curve: for example, if a child was in the 50th percentile by height and weight in early development, the affected child may fall into the 10th percentile over time.
As an example of the impacts of sleep disorders on normal growth, it is known that sleep apnea in children can have profound effects on growth. These children have periodic obstructions in their upper airway that can cause snoring or pauses in their breathing. The body awakens itself into lighter sleep to open the airway and resume normal breathing. As such, deeper sleep may become fragmented and growth hormone secretion may be compromised.
Sleep apnea in a child occurs when the muscles of the upper airway relax enough to temporarily reduce or obstruct airflow. This can occur repeatedly over the course of a night and result in disrupted sleep as the brain attempts to awaken the body and resume normal breathing. Both events can be associated with a drop in blood oxygen levels.
In children, sleep apnea is diagnosed when at least one apnea event occurs per hour of sleep as observed during a diagnostic sleep study. (For adults, more than five events per hour indicate apnea.)
Surprising signs of sleep apnea in children include mouth breathing, bedwetting, sleepwalking, restlessness, and sweating during sleep. There are also several potential consequences for a child's mental and physical health associated with sleep apnea.
Approximately 1% to 3% of preschool-aged children have sleep apnea.2 Apnea in children tends to peak between ages 2 and 6. Due to the course of normal growth during this period of time a child's tonsils and adenoids tend to be proportionately larger than their airway. This crowding makes the airway more easily obstruction.
The risk of sleep apnea also is higher in adolescents who are severely overweight or obese. Children of any age who have asthma or allergies also are more prone to developing sleep apnea.
Sleep apnea may increase sleep fragmentation, meaning that rather than experiencing the normal periods associated with each sleep stage, a child with apnea moves more frequently between deep and lighter stages of sleep. Research suggests that the long-term effects of sleep apnea in children include cognitive, behavioral, and psychosocial problems as well as growth delays and impacts on cardiovascular health.
Children with untreated sleep apnea may perform poorly on standardized tests of mental development. In a school-based study in India, children with sleep apnea were found to perform significantly less well in academic subjects than their peers. Other potential problems with intellectual development include lower scores on learning and memory metrics and on some types of intelligence quotient (IQ) tests. Children with the most severe apnea appear to also experience the most significant challenges to cognitive development.
Unlike in adults—who become sleepy and sedate with sleep deprivation—children tend to become hyperactive. This may cause difficulties with attention and social behavior and may also contribute to anxiety and depression. Hyperactivity resulting from sleep apnea in children sometimes is misdiagnosed as Attention Deficit and Hyperactivity Disorder (ADHD).
An English study in the Journal of Thoracic Disease also showed that children with untreated apnea were more likely to exhibit poor social and communication skills and have difficulty regulating their behaviors. These traits are often experienced by caregivers as uncooperativeness or emotional volatility.
When sleep apnea continues over a long period in childhood, increasing markers of inflammation can also be found. Inflammation, in turn, can lead to a cascade of negative health outcomes such as compromised organ function.
A child who is not getting enough restorative sleep at night could show signs of excessive sleepiness during the day. Babies and children need different amounts of sleep based on their age and stage, but if you notice your child napping longer or more frequently than usual or seeming tired when he or she is normally energetic, apnea could be the cause.
Sleep-disordered breathing in children is associated with negative effects on growth. Children with apnea may lose ground among their peers, or slow along their previous growth path, resulting in an inability to meet their full growth potential. This may be caused by frequent awakening from deep, slow-wave sleep which in turn could disrupt normal hormonal secretion, including growth hormones. In extreme circumstances, a child with apnea whose growth falls far below healthy levels may be diagnosed with failure to thrive.
When sleep is disrupted in young children, especially those who have yet to finish growing, there can be significant consequences. Growth hormone is secreted during the night during specific sleep stages. Deep, non-REM sleep that occurs early in the night seems especially important for its secretion. This sleep predominates in the first third of the night. If this sleep is disrupted, growth may not occur normally. Children who are affected may begin to fall off their growth curve: for example, if a child was in the 50th percentile by height and weight in early development, the affected child may fall into the 10th percentile over time.
As an example of the impacts of sleep disorders on normal growth, it is known that sleep apnea in children can have profound effects on growth. These children have periodic obstructions in their upper airway that can cause snoring or pauses in their breathing. The body awakens itself into lighter sleep to open the airway and resume normal breathing. As such, deeper sleep may become fragmented and growth hormone secretion may be compromised.
Any sleep disorder that disrupts deep sleep may decrease growth hormone secretion. Moreover, simply not getting enough sleep could have the same effects. Fortunately, children whose sleep apnea is treated undergo a rebound growth spurt. Many will recover to their prior growth trajectory, moving back to their prior percentiles. This suggests that addressing the other conditions that undermine sleep quality, such as restless legs syndrome, may likewise be beneficial.
The risk of sleep deprivation causing obesity has been well studied in adults. Although the mechanism is not fully understood, it may relate to hormonal changes or effects on normal metabolism. A similar association appears to exist in children. When children don't get enough sleep at night to meet their age-based sleep needs, they are at risk of undermining their overall health.
Over the past 20 years, many independent studies of more than 50,000 children support the fact that sleep deprivation appears to be associated with an increased risk of obesity. In 2002, a study of 8,274 Japanese children who were 6-7 years old showed that fewer hours of sleep increased the risk of childhood obesity.
These consequences appear to persist beyond the period of sleep disruption. In 2005, a study showed that sleep deprivation at age 30 months predicted obesity at age 7 years. The researchers hypothesize that sleep disruption may cause permanent damage to the area of the brain called the hypothalamus, which is responsible for regulating appetite and energy expenditure.
The risks of untreated sleep disorders should prompt careful attention by parents to any signs that their child is not getting enough quality sleep. If you suspect a problem, you should speak with your pediatrician. A careful evaluation may offer some reassurance, and when treatment is indicated, it may help your child to grow and thrive.
Growth hormone deficiency (GHD) results when the pituitary gland produces an insufficient amount of growth hormone. Although most common in children born with the disorder, known as congenital GHD, growth hormone deficiency can develop later in life (acquired GHD). Congenital GHD causes delays in growth, short stature, and other signs of slowed physical maturation. Although GHD does not directly affect intellectual ability, some children also may experience learning and other delays. In adults, symptoms of acquired GHD range from reduced energy levels to osteoporosis and impaired cardiac function. Congenital GHD is caused by a genetic defect, while acquired GHD most often results from brain trauma or a pituitary gland tumor. The standard treatment for growth hormone deficiency is daily injections of recombinant human growth hormone (rHGH).
A child born with congenital GHD will have different symptoms than an adult who develops the disorder later in life. For children, one of the tell-tale symptoms, shorter-than-average stature, arises because the condition slows the rate at which the bones of the arms and legs grow.
• A large forehead (due to incomplete closure of the skull)
• Slowed development of facial bones, including a small or underdeveloped nose
• Delayed growth of adult teeth
• Fine or sparse hair
• Insufficient nail growth
• High-pitched voice
• Excess of abdominal fat
• Delayed puberty
• Although very rare, a micropenis in boys
• Decrease in energy
• Changes in body composition — specifically an increase in abdominal and visceral fat and a decrease in lean body tissue
• Reduced muscle strength
• Osteoporosis
• Increased blood cholesterol levels
• Insulin resistance
• Impaired cardiac function
• Sexual dysfunction
• Depression or anxiety
Congenital growth hormone deficiency is caused by a gene mutation that can be passed along by both or either parents, depending on the specific mutation. Three genetic defects are known to be responsible for GHD: growth hormone deficiency IA, growth hormone deficiency IB, or growth hormone deficiency IIB. Congenital GHD also can result from brain defects that lead to inadequate development of the pituitary gland.
There are a number of potential causes of acquired GHD. Among them are:
• Brain trauma
• Infections of the central nervous system
• Pituitary gland tumors
• Hypothalamus tumors
• Systemic diseases such as tuberculosis or sarcoidosis
• Cranial irradiation
Sometimes an exact cause of growth hormone deficiency cannot be identified, in which case it is referred to as "idiopathic GHD."
There are important differences in the diagnostic process for children and adults. For children, whose overall health is evaluated at yearly checkups, a suspicion of GHD is easily ascertained when they clearly are lagging behind other kids their age based on growth charts and other measures of normal development and/or show other symptoms of growth hormone deficiency. Medical history and physical examination (specifically height velocity, or speed of growth) are the primary drivers of diagnosis in children. In adults, medical history and physical examination are also important to rule out other diseases.
If a physician decides a blood test is necessary, growth hormone deficiency may be diagnosed by assessing for insulin-like growth factor (IGF-1) and growth factor binding protein (IGFBP-3). But because levels of growth hormone fluctuate throughout the day, GHD cannot be diagnosed by simply measuring the amount of hormone in a blood sample.
Medication may be used to stimulate the pituitary gland to release growth hormone. The effect this has on blood levels are then evaluated. If the medication produces a minimal (or no) increase in growth hormone, a diagnosis of GHD can be confirmed, although more testing may take place to rule out other potential causes of delayed growth, such as a thyroid disorder. A child also may undergo imaging tests to evaluate the growth plates in their bones.
There are two specific stages at which children typically are diagnosed with GHD: The first is around age 5 when a child begins school and it becomes apparent, they are smaller than their classmates. The second is related to puberty: For boys, that means between 12 and 16, for girls between 10 and 13.
Symptoms caused by growth hormone deficiency in adults are less obvious and can easily be related to other disorders. For this reason, acquired GHD in an adult usually is discovered during a general evaluation of a pituitary function that is being done because of symptoms or signs of the thyroid, adrenal, or sexual dysfunction.
Growth hormone deficiency is primarily treated with daily injections of recombinant human growth hormone (rHGH). (The generic name for rHGH is somatropin; brand names include Genotropin, Humatrope, and others).
For children, treatment begins once a diagnosis is made and is continued over the course of several years, which greatly increases the chance they will attain a relatively normal rate of growth and development. The dosage prescribed is increased during this time, reaching a peak around puberty, after which treatment typically is discontinued.Children who have developmental disorders associated with GHD usually will require targeted treatment for those co-existing problems, such as:
• Physical therapy for delays in walking and strength
• Occupational therapy for self-feeding, dressing, toileting, and learning
• Speech therapy to address weakness in mouth and facial structures that may impact swallowing and talking
Whether growth hormone deficiency is congenital or acquired (or idiopathic), it is a relatively easy disorder to diagnose and treat. The likelihood most children born with GHD who begin growth hormone injections early will catch up with their peers physically and developmentally is high. The prognosis isn't as cut-and-dried for adults, given some who develop GHD may not know it until they develop serious complications, but it still is comforting to know that they can be treated as easily as children.