It is undisputed that high levels of lead in the body of an infant or toddler can lead to brain damage.
Now new research from the University of Pennsylvania School of Nursing shows lead exposure can increase risk of persistent sleep problems in children and teens. The problems include insomnia, trouble falling asleep and staying asleep, waking up very early, having to use sleeping pills and even excessive sleepiness during the day.
The study, to be published in the December issue of the journal SLEEP, was conducted in four elementary schools in Jintan City, China. The study began in 2004 and involved 1,419 children.
Researchers said lead exposure has been pervasive in China.
The study showed poor sleep issues occurred two to three times as frequently for the children who had blood lead levels (BLL) above 10 micrograms per deciliter. This level is the same one used by the California Department of Public Health as a sign that living conditions for children are extremely dangerous and in need of immediate intervention, as KPCC reported in a series on lead exposure in South Los Angeles.
The blood of 665 children was tested for lead for the study when they were between 3 and 5 years old. Their sleep was assessed when they were between 9 and 11 years old. Children and parents both answered questionnaires about the kids' daily sleep patterns.
“Little is known about the impact of heavy metals exposure on children’s sleep, but the study’s findings highlight that environmental toxins – such as lead – are important pediatric risk factors for sleep disturbance,” stated Jianghong Liu, associate professor at the U-Penn School of Nursing and the study’s principal investigator.
While sleepiness might not seem as harmful as brain damage, researchers said sleep issues are a “significant public health burden.” They also said more research needs to be done to identify other factors contributing to the sleep problems.