Physiology and Pharmacology professor John Ciriello’s research shows pregnant women suffering from sleep apnea may actually be putting their unborn children at risk for metabolic diseases as adults.
Sleep apnea is a disorder in which breathing repeatedly stops during rest, thus depriving the body of oxygen.
“Normal oxygen levels are around 98 per cent. But that drops down to 90, or even 88, during a period of time for those with sleep apnea,” Ciriello said. “That’s what people don’t seem to understand – those who have sleep apnea, on record, lose about 10 years of their lives because it leads to metabolic disorders, such as high blood pressure. That’s what kills you in the end.”
Clinicians must ‘wake up’ and understand that sleep apnea should be considered one of the components in the metabolic syndrome, Ciriello argued. These clusters of conditions (including increased blood pressure, a high blood sugar level, excess body fat around the waist and abnormal cholesterol levels) increase the risk of heart disease, stroke and diabetes.
For his study, Ciriello observed female rats and their offspring. The team exposed female rats to intermittent bouts of no oxygen as soon as they became pregnant. The researchers observed the offspring of those rats had higher levels of proteins that encourage the liver to release, and not store, glucose. This suggested reoccurring oxygen deprivation – as the type that occurs in sleep apnea – during pregnancy can cause long-term changes in the offspring’s liver function.
“One of the things we’ve been looking at is, what happens over these longer periods of time,” Ciriello said. “What we have shown is they (offspring) become leptin resistant. That is a fat hormone that signals the brain and says ‘I have had enough and don’t eat anymore.’ Over time, the signal doesn’t work anymore, so the leptin doesn’t trigger the brain to say ‘stop.’”
The research team has followed the effects into adulthood, noting at 12 weeks old the offspring of mothers exposed to chronic intermittent hypoxia were hyperglycemic (excessive amount of glucose) and hyperinsulinemic (excess levels of insulin).
“These adult offspring have a decreased sensitivity to insulin, but have not developed a complete resistance to its signalling effects at this age,” Ciriello said. “This further supports our suggestion that adult offspring of mothers exposed to chronic intermittent hypoxia during gestation are at a higher risk for developing some aspects of the metabolic syndrome, including Type 2 diabetes.”
He added, “That was totally unexpected. It was a eureka moment. We did not expect these changes to occur. We thought there might be a slight change at birth, and that things would work themselves out. But that was not the case, because we followed them into adulthood and they’re in bad shape.”
Individuals with severe sleep apnea can experience numerous bouts of oxygen deprivation throughout the night, each one a duration of up to 30-40 seconds without breathing.
“Just think of holding your breath for about 30 to 40 seconds, say 100 times,” he said, noting in cases such as this a person would require a CPAP (continuous positive airway pressure) device. “The problem with that is the compliance, where we’ll see in three to six months, the person stops using it. Because you are forcing air in them, people feel they are getting bloated, or their partner doesn’t like the noise.”
In mild cases, people can attempt sleep on their sides or use a mouth guard to bring out the jaw line in an attempt to maintain the airway.
Ciriello will look further into the effects of sleep apnea, but hopes his initial findings spark awareness of the consequences it can have on children as they grow.
“Whenever I talk to physicians, or those who deliver babies, I say ‘Do you ever ask the female if she’s ever suffered from sleep apnea?’ The answer is ‘no.’ It never appears on a form,” he said. “There are a lot of things we are exposed to in the media and we simply tend to blame the most obvious things. Maybe we should be looking at ourselves more closely. We’ve blamed McDonalds all our lives for all the problems we have. Maybe it’s not; maybe it’s as simple as mom not breathing properly during pregnancy.”