Severe sleep apnea in PWS children strongly linked to extra weight: Study
BMI management key to improving breathing disruptions, researchers say
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Sleep apnea, or breathing disruptions during sleep, is common in children with Prader-Willi syndrome (PWS) and is more severe than it is in children with sleep apnea but no PWS, according to a study in China.
In the PWS group, a higher body mass index (BMI), a ratio of weight and height used as a proxy of body fat, was significantly associated with more severe obstructive sleep apnea (OSA) and lower nighttime oxygen levels. OSA is when breathing stops and starts during sleep due to airway blockages.
“These findings highlight the critical role of obesity in exacerbating respiratory compromise and emphasize the necessity of routine PSG [polysomnography] screening and targeted BMI management in PWS care,” researchers wrote. PSG, or sleep study, records brain waves, blood oxygen levels, heart rate, and breathing during sleep.
The study, “Severity and phenotype of sleep-disordered breathing in Prader-Willi syndrome compared to obstructive sleep apnea syndrome in children,” was published in the journal Respiratory Medicine.
Sleep-related breathing disorders very common in PWS
PWS is a complex genetic disease marked by a range of symptoms, including weak muscle tone, poor growth, developmental and learning challenges, and excessive hunger, which often leads to obesity.
Sleep-related breathing disorders are very common in PWS. Studies suggest that between 44% and 100% of people with PWS have some form of sleep-disordered breathing, far higher than the 2% to 3% frequency seen in the general population.
These issues can include OSA, central sleep apnea — which is caused by impaired communication between the brain and breathing muscles — and hypopneas, or shallow breathing during sleep.
Sleep-related breathing disorder “is a significant contributor to exacerbations and mortality in children with PWS,” the researchers wrote. “However, its clinical characteristics, risk factors, and impact on sleep architecture remain incompletely understood.”
BMI values of PWS children higher than those of control group
To fill this knowledge gap, a team of researchers retrospectively analyzed data from 16 children with PWS (nine boys and seven girls; age range 3.4 years to 14.7 years) who underwent polysomnography at a single Chinese hospital between December 2020 and January 2025.
A group of 32 age- and sex-matched children diagnosed with obstructive sleep apnea syndrome (OSAS) during the same period, and without underlying diseases, were included as a control group. OSAS refers to the clinical condition characterized by physical airway obstruction and associated symptoms, such as excessive daytime sleepiness and cognitive impairment.
Children with PWS had a median BMI of 24.5 kg per square meter, which generally falls in the overweight or obese classification for their age range, suggesting excess body fat. Their BMI values were significantly higher than those of the control group (median of 18.6 kg/square meter).
There were no significant group differences in the rates of enlarged tonsils or adenoids, distinct immune structures in the throat and nasal passage that can obstruct airways and lead to sleep apnea when enlarged.
Based on sleep study results, all children with PWS were diagnosed with OSAS, and none met criteria for central sleep apnea.
On sleep studies, total sleep time and sleep efficiency were similar between the PWS and control groups, but children with PWS spent significantly less time in deep sleep, which is especially important for physical restoration, growth, and recovery.
Our study indicates that obesity is a key factor for PWS-related [sleep disordered breathing]. Clinicians should integrate weight management strategies with respiratory therapies to optimize outcomes in this patient group.
The PWS group also had significantly lower average and minimum oxygen levels during the night and a significantly higher oxygen desaturation index, meaning their oxygen levels dropped more often and more severely.
Breathing interruptions were also more pronounced in the PWS group. Their obstructive apnea-hypopnea index (OAHI), which measures the number of respiratory events per hour of sleep, was significantly higher than that of children with OSAS but no PWS.
Also, the PWS group was significantly more likely to have moderate-to-severe OSAS (75% vs. 18.8%). Indices for central, obstructive, and mixed apneas, as well as hypopneas, were all significantly higher in the PWS group.
Further statistical analysis in children with PWS showed that a higher BMI was significantly linked to a higher OAHI and hypopnea index, reflecting more sleep-disordered breathing, and significantly lower minimum oxygen levels.
Adenoid enlargement was also significantly associated with a higher OAHI, while tonsil enlargement did not show a clear relationship with any sleep study parameters.
“Our study indicates that obesity is a key factor for PWS-related [sleep disordered breathing],” the researchers wrote. “Clinicians should integrate weight management strategies with respiratory therapies to optimize outcomes in this patient group.”
Still, more research is needed to determine whether respiratory problems in PWS stem solely from obesity or from a combination of contributing factors, the team concluded.
