Sleep Disorders in Children

Sleep and wakefulness are governed by a complex neurobiologic system typically conceptualized as the "two-process model".
Process S (Homeostatic Process): Regulates the length and depth of sleep, driven by the accumulation of sleep-promoting chemicals (somnogens) like adenosine during wakefulness.
Process C (Endogenous Circadian Rhythms): Influences the internal organization of sleep and governs predictable patterns of alertness and the timing of daily sleep-wake cycles.

Insomnia involves difficulty initiating or maintaining sleep despite age-appropriate opportunities, resulting in daytime functional impairment.
Sleep-Onset Association Type: The infant or toddler learns to fall asleep only under specific conditions (e.g., being rocked, fed, or requiring parental presence) and fails to develop self-soothing capabilities. During normal nighttime brief arousals, the child cannot return to sleep without those exact associations.
Limit-Setting Type: Common in preschool and school-aged children, characterized by stalling and refusing to go to bed. This is frequently related to inadequate parental limit-setting or inconsistent bedtime rules.
Management: Behavioral interventions are the first-line treatment. Strategies include establishment of a set sleep schedule, positive reinforcement, and extinction (rapid or graduated withdrawal of parental assistance at sleep onset). Pharmacotherapy (e.g., melatonin) is infrequently needed for typically developing children but may be an effective adjunct in children with autism spectrum disorder or attention-deficit/hyperactivity disorder (ADHD).

OSA is characterized by repeated episodes of prolonged upper airway obstruction during sleep despite continued respiratory effort, causing complete (apnea) or partial (hypopnea) cessation of airflow.
Etiology: Results from decreased upper airway patency (commonly due to adenotonsillar hypertrophy), increased upper airway collapsibility (e.g., neuromuscular hypotonia), or decreased central ventilatory drive. Obesity is a major risk factor due to pharyngeal fat pads and increased neck circumference.
Clinical Features: Nocturnal symptoms include loud snoring, gasping arousals, restless sleep, and diaphoresis. Daytime sequelae prominently include neurobehavioral deficits such as daytime sleepiness, irritability, hyperactivity, impulsivity, and poor concentration, which heavily overlap with ADHD symptoms.
Diagnosis and Management: The gold standard for diagnosis is an in-lab overnight polysomnogram (PSG). Adenotonsillectomy is the first-line treatment for children with adenotonsillar hypertrophy. Continuous positive airway pressure (CPAP) and weight loss are indicated for residual disease or when surgery is contraindicated.

Parasomnias are episodic nocturnal behaviors involving cognitive disorientation and autonomic or skeletal muscle disturbances.
They are broadly divided into non-rapid eye movement (NREM) partial arousal parasomnias and REM-related parasomnias.

Feature	NREM Parasomnias (Sleep Terrors / Sleepwalking / Confusional Arousals)	REM Parasomnias (Nightmares)
Timing in Sleep Cycle	First third of the night (during slow-wave/deep sleep).	Last third of the night (during REM sleep).
Presentation	Sudden onset with autonomic arousal (tachycardia, diaphoresis), ambulation, or thrashing.	Frightening dreams resulting in full awakening.
Memory of Event	Complete amnesia for the event.	Vivid recall of the dream.
Response to Comfort	Child avoids or exhibits increased agitation with parental comforting.	Child seeks and is comforted by parental reassurance.
Management	Parental education, reassurance, safety precautions (locks, gates), and scheduled awakenings. Pharmacotherapy is rarely indicated.	Reassurance and management of any underlying psychosocial stress.

Restless Legs Syndrome (RLS): An urge to move the legs accompanied by an uncomfortable sensory component (tingling, crawling), exacerbated by rest or inactivity, and peaking in the evening.
Periodic Limb Movement Disorder (PLMD): Characterized by periodic, repetitive, highly stereotyped limb jerks (e.g., rhythmic extension of the big toe and ankle dorsiflexion) occurring during sleep, leading to frequent arousals.
Management: Both disorders are highly associated with low serum iron/ferritin levels; management includes iron supplementation, avoidance of exacerbating substances (e.g., caffeine, antidepressants), and in severe cases, dopaminergic medications or alpha-agonists.

Narcolepsy is a chronic neurological disorder presenting in adolescence or early adulthood, characterized by profound, irresistible daytime sleepiness ("sleep attacks").
Type 1 Narcolepsy (with Cataplexy): Associated with a specific deficit in hypocretin/orexin in the lateral hypothalamus. Cataplexy is a sudden, brief loss of skeletal muscle tone triggered by strong positive or negative emotions.
Other Features: Hypnagogic/hypnopompic hallucinations, sleep paralysis, and disrupted nocturnal sleep.
Diagnosis and Management: Diagnosed via PSG followed by a Multiple Sleep Latency Test (MSLT) showing shortened sleep latency and sleep-onset REM periods. Management involves scheduled daytime naps and wake-promoting medications (modafinil, psychostimulants). Antidepressants or sodium oxybate may be used to treat cataplexy.