“This is kind of scary,” according to a medical scientist who studied how, if at all, poor sleep quality during the third trimester of pregnancy affects the lifelong health of a woman’s offspring. The study found that the male offspring of sleep-deprived mothers were more likely than the offspring of well-rested mothers to be overweight and suffer life-threatening metabolic disorders in mid-life.

The findings are “scary” to David Gozal, MD, a professor of pediatrics at the University of Chicago. Gozal’s study involved mice since it would take 50 years or more to study the effect in humans but his findings are noteworthy for humans just the same.

Many women experience difficulty sleeping as pregnancy draws toward childbirth, some to a “profound” degree, according to Gozal. “We wanted to devise a system that enabled us to measure the potential impact of fragmented sleep on the fetus, which is uniquely susceptible so early in life,” he said.

Gozal’s experiment involved two sets of mice during days 15 through 19 of their pregnancies. This day range in mice is equivalent to the third trimester in a human pregnancy.

One group of mice was allowed to sleep peacefully but the other group had their sleep cycles repeatedly disrupted to simulate the sleeping experience of a human with sleep apnea, a condition many human mothers experience in the third trimester.

To systematically disrupt the sleeping mice, their cages were fitted with a brush that swept through it at two-minute intervals during the entire sleep cycle. Each time the brush swept through, the sleeping mouse had to wake up and jump over it.

At birth, the offspring from both groups seemed similar, weighing about the same, feeding normally, and growing as expected. Problems developed, however, when the male offspring of sleep-deprived mothers reached 16 to 18 weeks of age (middle age in human time). The researchers limited their study to male offspring only because the male hormone system is simpler than a female’s and easier to track.

Eventually, metabolic changes began to develop in the offspring of sleep-deprived mothers and they started gaining excess weight. By week 24, these mice had gained an excess of about 10% of their body weight on average, or roughly 15 pounds in a human. This amount of weight gain isn’t extreme but it’s enough to trigger metabolic changes that lead to morbid obesity and type 2 diabetes in mice and humans alike. Some of the mice had become morbidly obese and died much sooner than their more slender counterparts.

Several metabolic changes were of particular interest to Gozal:

  • The mice became insulin-resistant, a condition that signals metabolic syndrome and diabetes.
  • They developed disproportionately high ratios of visceral white adipose tissue, the “bad” type of belly fat.
  • They had high levels of low-density lipoproteins, the “bad” kind of cholesterol often designated as LDL.
  • These abdominal fat cells produced low levels of adiponectin, a hormone beneficial in reducing cholesterol and regulating glucose metabolism.

An in-depth study revealed epigenetic changes influenced by environmental factors. In this case, the changes were triggered by their mothers’ sleep deprivation during late pregnancy.

The study leaves Gozal questioning, "Will this generation, the sons of sleep-deprived mice, who are already at increased risk for metabolic syndrome and type 2 diabetes, transmit this inherited risk, perhaps compounded by new stresses, to their offspring?"

Source: Gozal, David, et al. “Sleep Fragmentation During Late Gestation Induces Metabolic Perturbations and Epigenetic Changes in Adiponectin Gene Expression in Male Adult Offspring Mice.” Diabetes. American Diabetes Association. May 8, 2014. Web. Jun 8, 2014.