Israeli doctors link secondhand smoke to poorer sleep quality in children

Exposure to cigarette smoke at home is associated with poorer sleep quality among children, according to an Israeli study that measured tobacco exposure through biological markers.

Previous research linked secondhand smoke exposure to higher rates of snoring, insomnia and sleep-disordered breathing, but many of those studies relied mainly on parent reports or home monitoring.

Researchers at Ben-Gurion University of the Negev and Soroka-University Medical Center in Beersheva combined overnight sleep laboratory testing with a biological marker of tobacco smoke exposure, allowing them to directly measure the relationship between secondhand smoke exposure and children’s sleep.

The research was led by Professor Ariel Tersiuk of Ben-Gurion University’s Faculty of Health Sciences and director of Soroka’s Sleep Disorders Unit, together with Professor Aviv Goldbart, director of Soroka’s Pediatrics Department and a pediatric pulmonology specialist at Ben-Gurion University. The findings were published in the peer-reviewed Scientific Reports.

The study examined 30 children ages 1 to 12 who had been referred to a sleep laboratory because of symptoms including snoring, suspected obstructive sleep apnea and other breathing-related sleep complaints. Nearly half lived in households where at least one parent smoked.

The researchers combined an overnight sleep study known as polysomnography, which measures brain activity, breathing, heart rate, oxygen levels and other bodily functions during sleep, with parental questionnaires and urine tests measuring cotinine, a nicotine byproduct that serves as an objective marker of tobacco smoke exposure.

The results revealed a clear dose-response relationship. The higher a child’s cotinine level, the lower the child’s sleep efficiency and the shorter the total sleep time. Children exposed to cigarette smoke also had a 67% higher arousal index, meaning their sleep was interrupted more frequently throughout the night.

Interestingly, the researchers did not find that secondhand smoke made obstructive sleep apnea itself more severe among the children studied. Sleep apnea is a disorder in which breathing repeatedly stops or becomes reduced during sleep, often due to a blocked airway. Researchers had believed cigarette smoke would irritate and inflame the airways, potentially making breathing problems during sleep more severe.

Instead, the smoke appeared to fragment the children’s sleep, causing more frequent awakenings.

“The worrying thing is that the smoke doesn’t stay outside the children’s room,” Tersiuk said. “Even when a parent is convinced that they are ‘smoking carefully,’ it results in more awakenings, less deep sleep and fewer opportunities for real rest.”

The study also uncovered a significant gap between measured exposure and parental awareness. Although urine tests showed clear evidence of tobacco smoke exposure, 60% of parents denied that their children were exposed to cigarette smoke.

The researchers said the discrepancy highlights the need to improve public awareness about how smoke lingers indoors and continues to affect children after a cigarette has been extinguished.

“Parents tend to see snoring as something momentary and disturbing, but for many children it is just the tip of the iceberg,” Goldbart said. “When cigarette smoke around the home is added, even if it is ‘in the background,’ sleep becomes more fragile and shorter.”

He added, “Passive smoking is a risk factor that can be stopped immediately, thereby significantly improving the quality of the child’s sleep and his daytime functioning.”

The research team noted that fragmented sleep in childhood has been linked to attention deficit disorders, learning difficulties and obesity, making the findings relevant beyond sleep medicine.

Dr. Iris Etzion, Dr. Noga Aruas and epidemiologist Dr. Shari Greenberg-Dotan, who participated in the clinical monitoring of the children, said physicians should routinely ask families about smoking habits when evaluating children with snoring, sleep apnea or other sleep disorders.

The researchers urged parents to maintain smoke-free homes, emphasizing that reducing children’s exposure to tobacco smoke is a simple preventive measure with important benefits for sleep, development and daily functioning.

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