Uncovering Sleep's Secrets

September 2, 2004

Heather Heilman
Phone: (504) 865-5714

Narong Simakajornboon in front a bed I think it's pretty interesting that we spend a third of our life sleeping, but we haven't really studied sleep very much," said Narong Simakajornboon.

Modern sleep research began about 50 years ago, but it's only been in the last decade that the medical community has really started to pay attention, thanks to studies showing a significant relationship between the quantity and quality of sleep and many health problems.

Insufficient sleep affects the secretion of hormones that are linked to obesity, for example. Interrupted sleep is associated with hypertension and cardiovascular problems.

Insufficient sleep also impairs the body's ability to use insulin, which can contribute to the onset of diabetes.

"What got me interested in sleep medicine were studies showing an association between sleep apnea in children and poor school performance, behavior problems and attention deficit and hyperactivity disorder as well as cardiovascular problems," said Simakajornboon.

He's a pediatric pulmonologist whose area of interest is the control of breathing. He's also the medical director of Tulane's Comprehensive Sleep Medicine Center. Sleep apnea is a condition in which the airway is obstructed during sleep, causing inhibition of breathing and frequent awakening during the night. Studies suggest that about 30 percent of kids with ADHD also have sleep disorders, which may be the cause of their hyperactivity.

According to a 2004 poll, American children seem to be getting less sleep than experts recommend. And the lack of sleep can put kids at risk for injuries and school problems. Up until the age of 12, kids need nine hours of sleep a night.

Parents might not realize that sleep is a problem when a child seems full of energy--but that can actually be the result of not getting enough sleep. According to Simakajornboon, Tulane's is the only pediatric sleep center in Louisiana.

Because of this, it tends to run more studies on children than adults. But Houman Dahi, who is currently finishing a fellowship at the center, will soon become director of the adult sleep lab and will work to expand that side of the center's research.

The sleep center is one of only 30 in the nation that trains fellows in sleep medicine, a growing, interdisciplinary field that draws researchers and clinicians from pulmonology, neurology, psychiatry and other fields.

Simakajornboon wants to help the field grow internationally, and helped begin a fellowship program in which foreign physicians come to Tulane to do sleep research. Last year, more than 700 overnight studies were performed at the center. Subjects may have to be monitored two nights in a row, because it takes a night to get acclimated.

"But you'd be surprised how well people can sleep in the lab," Simakajornboon said. The sleep lab is state-of-the-art, with the ability to monitor up to 50 channels on a subject, to capture everything from brain waves to eye movement to leg-twitching. "Because of that, we can look at some of the rare sleep disorders, like narcolepsy."

Narcolepsy is a condition that causes people to suddenly fall asleep at unexpected times. But they also see a lot of garden-variety sleep problems leading to sleep deprivation, one of the hazards of contemporary life. "The lightbulb drastically changed human life," said Simakajornboon. "Now you can work at night and sleep in the daytime."

But it doesn't seem to be that easy to change the body's circadian rhythm. Working during normal sleep time impairs alertness and performance and contributes to accidents. "People think sleep is a luxury but it's very important."

Simakajornboon has done sleep studies with children who have restless leg syndrome and periodic movement disorder, and found that iron supplementation can help. He has a project looking at sleep problems in children with cystic fibrosis.

Currently, his main research interest is the effect of prenatal nicotine exposure on babies. Sudden infant death syndrome, which occurs when babies are asleep in bed, is associated with in utero nicotine exposure.

"We see that nicotine has a great impact on breathing patterns in newborns," he said. "When we look at nicotine-exposed rat pups, we find they are not able to cope that well with low oxygen levels, sometimes to the point that cell death in certain areas of the brain occurs."

Simakajornboon is looking at the rat model to see how nicotine exposure alters neurotransmitters. He's also doing clinical sleep studies with young children of mothers who smoked while pregnant. Roughly a third of babies born pre-term were exposed to nicotine in the womb. Women who smoke may try to quit when they get pregnant by using a nicotine patch or gum, but Simakajornboon's studies suggest that nicotine in any form adversely affects the baby's respiratory control.

Tulane University, New Orleans, LA 70118 504-865-5000