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In recent years, as the field of pediatric sleep medicine has grown, more kids are getting the distinct pleasure of spending the night at sleep clinics, where sleepovers are less about movie marathons and Sharpie mustaches than obstructive hypopnoea and oral flow measurements. Best Friday ever.

Sometimes, personal history is sufficient to diagnose sleep disorders. In other cases, it's not enough to relay the details of little Moishe's night-thrashing and wheezing fits. Sleep specialists may need to cover teeny, cranky heads with electrodes to aid proper diagnosis and determine the best course of treatment.

A new paper, published in the journal Paediatric Respiratory Reviews, explains when to head to the clinic. Here's an overview:

The multi-part test performed in a sleep study is called polysomnography (PSG), in which doctors use use EEG, as well as airflow and respiration monitors, to measure factors relevant to dissecting rest: sleep architecture, gas exchange, respiratory events, snoring, arousals, limb movements, heart rate and body position. Basically, after all is said and done and measured and analyzed, sleep doctors should have an idea of what transpires after kids get tucked in, and how nocturnal weirdness relates to daytime well-being.

What behavior warrants a trip to the clinic?

Any signs of sleep apnea, a sleep breathing disorder in which airway obstruction interferes with normal nighttime ventilation and sleep patterns. In many cases, doctors will recommend the removal of adenoids and tonsils in kids diagnosed with sleep apnea. A sleep study can help confirm the diagnosis and inform treatment decisions regarding, for example, timing of the procedure and potential postoperative complications. A behavioral case history alone, the paper says, is a poor predictor of sleep apnea.

In children, hypoventilation disorders are often asymptomatic at first, revealing themselves later through respiratory failure, nocturnal arousal, awkward sleeping positions, night sweats, morning headaches, daytime drowsiness, daytime hyperactivity, behavioral and cognitive problems — even “failure to thrive.” Nocturnal hypoventilation can be congenital. It can also arise in relation to various health issues, including chronic lung disease, muscle weakness and brainstem abnormalities. The top causes of hypoventilation are diseases: muscular dystrophy, cystic fibrosis, scoliosis and obesity.

Sleep studies can help doctors evaluate respiratory status over time, as abnormal polysomnography results often precede more troubling daytime complications.

A sleep study, in conjunction with a subsequent “nap test,” is the best objective measure of excessive daytime sleepiness as an indicator of narcolepsy. While sleep diaries are useful too, it’s important to use PSG to rule out other causes of daytime lethargy, such as disordered breathing.

Restless Leg Syndrome can be hard to diagnose without a sleep study because kids might have trouble describing symptoms, including periodic limb movement exceeding five mph and daytime fatigue.

What behavior doesn’t?

Parasomnias, sleep movement disorders, including sleepwalking and night terrors. Most of the time, doctors can diagnose based on a behavioral history and, if necessary, home video recording. But some cases fall into the "better safe than sorry" category:

• If mini-parasomniacs are hurting themselves or others during their night-roving.
• If they have or are known to be at risk of epilepsy, because some bouts of nighttime movement can resemble epileptic episodes.
• If sleepwalking episodes follow other abnormal nocturnal behavior, such as snoring, bed-wetting or periodic leg movements.

Circadian Rhythm Disorders, such as delayed sleep-wake phase disorder, are typically diagnosed through personal history, sleep diaries and actigraphy, a non-invasive method of rest.