Silvana Pannain, MD

Background

Until a few years ago it was common thinking that sleep was important only ”from the chin up”, in other words for the brain and not for the rest of the body. In the last two decades the University of Chicago has pioneered breakthrough research looking at the effects of sleep on hormone secretion. Researchers asked if partial sleep deprivation (which many people undergo all the time) affected the risk of developing obesity and diabetes. This question was relevant seen that in the modern Western World there has been 1.) a rapid increase in the prevalence of overweight, obesity and diabetes with a significant impact in morbidity and mortality; 2.) a decrease in sleep duration due at least in part to self-imposed bedtime curtailment, seen also children and teens.

The U of C researches found that young, fit adults who habitually curtail their sleep are “metabolically aged” as their glucose tolerance is decreased and is comparable to that of a 60-80 year old who has impaired glucose tolerance.

More recent findings snagged headlines around the world when the same group showed that sleep-deprived subjects were hungrier, in particular for junk food, than when not sleep deprived . A detailed hormonal analysis provided a possible explanation by showing that the satiety hormone Leptin was decreased and the hunger inducing hormone Ghrelin was increased, in sleep deprived subjects. Lack of sleep deranges the hormonal control of appetite and could be linked to the worldwide epidemic of obesity. In support of the laboratory findings just described, several cross-sectional epidemiologic studies have suggested an association between short sleep and the increased prevalence of obesity and diabetes.

Research Interest

As part of this group of researchers I have been interested in sleep, glucose homeostasis and appetite regulation in the severely obese. In one unpublished study of severe obese subjects who had elected to have gastric bypass surgery to control their weight, subjects were required to eat a low calorie liquid diet and were given extended bed times. After 1 week, they reported that they were less hungry, even though they were eating far less calories that usual. In a study of sleep in severely obese subjects who did not have sleep disorder breathing we found that they felt more sleepy and that they had more fragmented and lighter sleep than age and gender matched controls. The poor sleep quality of the obese could generally result in an overall sleep loss.

My interests for future research are to look for interventions for weight management as a means of improving overall health. As reduced sleep has been shown to have deleterious affects I have proposed a study to look at whether extending sleep time and improving sleep quality will improve glucose homeostasis and appetite control in obese subjects using a pharmacologic agent which is known to improve sleep duration and quality.