NIH Sleep Deprivation Study Examines Gender Differences

It's more than a bit ironic that Jason Carter, chair and associate professor in exercise science, health and physical education at Michigan Technological University, has a touch of insomnia, since he is studying sleep deprivation in his lab.

Carter's malady may partially stem from having a new child at home; some 90 million Americans have such reason for such suffering. 

Whatever the cause, sleep deprivation can cause serious health problems. As part of a $400,000 grant from the National Heart, Lung and Blood Institute of the National Institutes of Health (NIH), Carter and his research team are looking at sleep deprivation's links to hypertension (high blood pressure), among other issues, and differences by gender.

"We are trying to figure out why women are more susceptible to developing hypertension as a result of reduced sleep, and it may relate to reproductive hormones," Carter says.

"In the women, we are looking at levels of estrogen and progesterone and if they relate to the sympathetic nervous system [the fight vs. flight response]," Carter says. "We don't know why women respond more dramatically to sleep deprivation from a cardiovascular perspective, but we aim to find out if an overly active nervous system is partially responsible."

The research focuses on differences in the nervous system's response to stress. Researchers can measure this response using a specialized technique called microneurography. This invasive procedure includes inserting a microelectrode into the peroneal nerve just below the skin surface in the lower leg. This provides them with direct measures of sympathetic traffic that can be quantified several ways.

The study will compare male and female subjects with a normal night's sleep and those who have been awake for twenty-four consecutive hours. For the stay-awake crowd, that means no coffee or food for the entire night, as the tired men and women camp out in the SDC under the watchful eye of students and researchers.

Master's student Robert Larson of Chassell assists Carter in the lab and focuses on "how sleep deprivation affects blood pressure and anxiety, and how your body responds to changes in blood pressure."

Sometimes the work gets comical. "The subjects can get loopy," Larson says. "We ask them to count backwards by fours, for example, and they can't do it."

Larson plans to earn a PhD and work with people in research labs in a hospital or academic setting.

The ramifications of sleep deprivation go beyond the lab, Carter says. If his work can lead to treatment for sleep-deprived women and men, that could in turn lead to lower health care costs, since many other health factors are impacted by a lack of sleep.

"Sleep medicine is really only a 20 to 30-year-old science," says Carter. "We are just beginning to realize the importance of getting a good night's sleep. There is a cumulative effect from not getting enough sleep."

And that seven to eight hours of sleep is becoming more elusive to Americans, he says, hence the urgency for his research and the NIH grant.

"We spend one-third of our lives asleep, and we still don't know the real physiological purpose."

Michigan Technological University is a public research university founded in 1885 in Houghton, Michigan, and is home to more than 7,000 students from 55 countries around the world. Consistently ranked among the best universities in the country for return on investment, Michigan’s flagship technological university offers more than 120 undergraduate and graduate degree programs in science and technology, engineering, computing, forestry, business and economics, health professions, humanities, mathematics, social sciences, and the arts. The rural campus is situated just miles from Lake Superior in Michigan's Upper Peninsula, offering year-round opportunities for outdoor adventure.