A child uses a puffer to control asthma symptoms.
When children have poorly controlled asthma symptoms, the condition can disrupt their sleep and lead to lower marks in school, according to the results of a U.S. study.
Although some experts have suspected that asthma could be detrimental to school work, this is the first study to systematically connect the dots between asthma, sleep and academic performance.
"We have been able to show that having asthma, when it is poorly controlled, can affect how children do in school, and we think that this can be explained, in part, by poor sleep," said the lead researcher, Daphne Koinis-Mitchell, an associate professor at Brown University's Alpert Medical School in Providence, R.I.
The study includes data from 170 asthmatic schoolchildren, aged 7 to 9, who live in the greater Providence area. Many of the children came from disadvantaged neighbourhoods. The researchers went to great lengths to measure asthma symptoms, quality of sleep and school activity.
Asthma symptoms, for instance, were charted over three 30-day monitoring periods during the school year using portable equipment that measured the amount and speed of exhaled air or lung function. The children and their caregivers also recorded symptoms in diaries. During the same time periods, sleep quality was determined with the use of a device that monitors body movements during the night. Plus, teachers kept reports of each child's behaviour and performance in school.
This type of detailed research doesn't come cheap: The study cost $2.5-million. It was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
As the researchers analyzed all the data, a clear pattern emerged. "Asthma corresponds to sleep and sleep corresponds to academic functioning," said Koinis-Mitchell, who presented her findings this week at a conference of the American Thoracic Society in Philadelphia.
Asthma is a chronic lung disorder in which the airways become inflamed and narrow, making it difficult to breathe. Environmental triggers ranging from pollen to cold air can make asthma symptoms worse.
She noted that asthma symptoms tend to increase at night for a variety of reasons. As part of the body's 24-hour circadian rhythm, immune cells involved in inflammation tend to increase at night. Going to bed can raise exposure to asthma triggers such as dust mites. And just the act of lying down can boost mucus production. All these factors can exacerbate breathing difficulties in children whose lungs are already inflamed by asthma.
Asthma is usually controlled with the routine use of daily and as-needed medications that reduce inflammation and bronchial constriction. Many of the study participants may have lacked access to regular medical care.
"Children can experience more symptoms at night because they are not taking their medications consistently," she said. "They end up missing sleep. When they wake, they are groggy, not alert and they attend school this way. That has an impact on their level of concentration. The quality of their work is compromised. In general, their academic function is negatively affected."
Children with poorly controlled asthma also tend to be absent from school more often than their healthy peers. "Because they are having adverse symptoms, many families keep their kids home. So they fall further behind in their school work and may not be able to catch up."
Even though the study was focused on children who mainly came from the urban poor, she said the findings would still apply to any child with poorly controlled asthma.
Koinis-Mitchell said it is important for schools to identify children who have asthma so they can get proper attention. But, she noted, many teachers don't know which of their students have the condition. "To be honest, they don't recognize that it matters. So they blame the difficulty concentrating on other issues, when it could be just a matter of poorly controlled asthma."