The purpose of this study is to look at the metabolic (use of energy) and hormonal features of sleep problems in men and women.
Obesity is a major risk factor for obstructive sleep apnea (OSA), a condition characterized by repetitive respiratory disturbances, intermittent hypoxia, sleep fragmentation by frequent microarousals and low amounts of deep slow wave sleep (SWS). Today, more than 10 million American women suffer from OSA. OSA has been identified as an independent risk factor for the metabolic syndrome. Because OSA is more prevalent in men than in women, a disproportionate number of studies of OSA and its consequences have been conducted in men. Thus, OSA has been characterized as a disorder associated with gender-based health care inequity. Recent evidence, including data from our group, suggests that reduced amounts and intensity of SWS (i.e. slow-wave activity \[SWA\]) may play a pivotal role in the development of metabolic and cardiovascular disturbances in obese men and women, particularly those with OSA. This project will focus on sex differences in SWA and their relationship with daytime sleepiness and metabolic vulnerability in obese men and women with and without OSA. We propose to simultaneously characterize: 1. sleep-wake regulation; 2. measures of diabetes risk; 3. measures of cardiovascular risk; and 4. profiles of sex steroids, cortisol and adipokines in a. obese men without OSA, b. obese men with OSA before and after treatment with continuous positive airway pressure (CPAP), c. obese pre-menopausal women without OSA, and d. obese pre-menopausal women with OSA before and after CPAP treatment. The completion of these interdisciplinary studies will provide a unique data set contrasting in obese women versus obese men the relationships between sleep and the metabolic syndrome, OSA and the metabolic syndrome and the impact of CPAP treatment on the metabolic syndrome. This work will provide important insights regarding the pathophysiology of OSA and its adverse consequences in obese men and women, and the basis for the development of effective sex-specific prevention and treatment strategies.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
27
CPAP (continuous positive airway pressure) treatment at home for 6 weeks
University of Chicago Department of Medicine, Section of Endocrinology, Diabetes & Metabolism
Chicago, Illinois, United States
Polysomnography - Apnea-hypopnea Index (AHI)
apnea-hypopnea index: number of apneas and hypopneas per hour of recording; a measure of the severity of obstructive sleep apnea; varies from min=0 to max=120; AHI between 0 and \<5: no significant sleep apnea; AHI between 5 and \<15: mild sleep apnea; AHI between 15 and \<30: moderate sleep apnea; AHI of 30 and above: severe sleep apnea.
Time frame: After 6 weeks of CPAP (Treatment)
Polysomnography - Minutes of N3 Stage
Stage N3, sometimes referred to as "delta sleep" or "slow wave sleep", is characterized by slow waves in the electro-encephalogram (EEG) that reflect synchronization of firing of cortical neurons. N3 sleep is considered the most restorative stage of sleep for both the brain and the rest of the body.
Time frame: After 6 weeks of CPAP (Treatment)
Polysomnography - Minutes of REM Stage
Time frame: After 6 weeks of CPAP (Treatment)
Polysomnography - Sleep Efficiency
Sleep efficiency: a measure of objective sleep quality; calculated from the polygraphic sleep recording as the ratio of time spent asleep during the scheduled sleep period to total scheduled sleep period. Expressed in %. Varies from 0% (the subject did not sleep at all) to 100% (the subject spent the entire scheduled sleep period asleep).
Time frame: After 6 weeks of CPAP (Treatment)
IVGTT (Intravenous Tolerance Test) - Sensitivity Index (SI)
Sensitivity Index (SI): a measure of how much insulin the body needs to metabolize a given amount of glucose. SI is calculated using a mathematical model describing the profiles of blood glucose and serum insulin after intravenous glucose injection. SI varies from 0 to an undefined upper limit but generally under 20. Higher values of SI represent a better outcome.
Time frame: After treatment (6 weeks)
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IVGTT (Intravenous Tolerance Test) - Acute Insulin Response
Acute Insulin Response is calculated as the area under the insulin curve for the first 19 minutes after intravenous glucose injection. "Area under the insulin curve" is expressed in pmol x min/L.
Time frame: After treatment (6 weeks)
IVGTT (Intravenous Tolerance Test) - Disposition Index (DI)
Disposition Index (DI) is the product of sensitivity index (SI) by the amount of insulin secreted in response to blood glucose levels. It is a marker of the risk of type 2 diabetes. Low DI reflects a high risk of diabetes. DI can vary from 0 to an undefined upper limit. The physiological range for the Disposition Index is 500 to 5,000. Higher values represent a better outcome.
Time frame: After treatment (6 weeks)