Cedars-Sinai scientists have found that proper sleep is as essential as diet and exercise for managing one’s weight, preventing Type 2 diabetes and maintaining good health. Conversely, they also have found that a lack of sleep could lead to insulin-resistant fat cells, the kind found in people who are obese or diabetic.
Studying the effects of both sleep loss and a diet high in saturated fat, researchers are looking at the tissue level for underlying mechanisms that signal the changes in fat cells.
Josiane Broussard, PhD, is a sleep scientist at the Cedars-Sinai Diabetes and Obesity Research Institute (DORI), focused on finding the metabolic events leading to insulin resistance. In the DORI lab, crossover studies are performed using animal models. The subjects begin at a healthy, similar size. Sleep studies are performed by allowing the subjects normal sleep sessions followed by varying times of sleep deprivation. The effects of sleep time on glucose tolerance and insulin sensitivity are measured.
After the initial sleep studies, subjects are fed a diet high in saturated fat, matching the fat composition of an American diet. Following six months of this fat feeding, the sleep studies are performed again.
Broussard is examining variations of sleep loss and fat feeding to connect how both stressors lead to insulin resistance.
Current DORI sleep and metabolism studies include:
- Effects of sleep loss on insulin sensitivity before and after a diet high in saturated fat
- Examine impact of sleep deprivation on insulin sensitivity.
- Feed a healthy diet that maintains subjects’ weight and analyze metabolic reaction to full sleep versus sleep loss.
- Following normalization period after sleep study, begin fat feeding and analyze metabolic function after six weeks.
- Determine level of metabolic dysfunction from sleep deprivation compared with a diet high in saturated fat.
- Suppression of nocturnal free fatty acids (FFAs) after a diet high in saturated fat
- Examine nocturnal FFAs as potential signal for β-cell compensation during high fat feeding.
- Feed a diet high in saturated fat, mimicking the Western diet and inhibiting feeding at night for six weeks, and analyze metabolic function.
- Introduce nocturnal FFA-suppression agent and analyze metabolic function.
- Determine whether nocturnal FFA signal increased β-cell function during fat feeding.
- Effects of "healthy" fat feeding on insulin sensitivity and secretion
- Examine the effect of a diet high in polyunsaturated fat (salmon oil) on insulin resistance, β-cell function and fat deposition.
- Collect measurements during control diet, then add either saturated fat diet of lard or unsaturated fat diet of salmon oil, using caloric equivalent.
- Determine whether there are metabolic differences based on fat feeding composition.
Results from these studies may help illuminate metabolic changes due to sleep loss and fat feeding different types of fat. This knowledge will guide future research to help scientists better understand the development of obesity and diabetes.