Effects of CPAP on Diet, Physical Activity, and Cardiovascular Risk
Effects of CPAP on Diet, Physical Activity, and Cardiovascular Risk
Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete
 loss of airflow during sleep, due to narrowing or closure of the upper airway. The resulting
 hypoxia has many cardiometabolic consequences, and leads to a disruption of sleep quality
 including reductions in the expression of rapid eye movement (REM) sleep and slow wave sleep
 (SWS). Patients also frequently experience excessive daytime sleepiness (EDS), which, when
 present with OSA, defines the clinical entity OSA syndrome (OSAS). Obesity is the leading
 risk factor for the development of OSA. Interestingly, it has been suggested that the
 disorder itself may contribute to further weight gain, presenting a vicious cycle wherein OSA
 and obesity perpetuate each other. OSAS may promote weight gain by placing patients in a
 state of positive energy balance characterized by low levels of physical activity and
 disrupted patterns of appetite-regulating hormones. Continuous positive airway pressure
 (CPAP), the gold-standard treatment of OSAS, may improve energy balance in these patients,
 although this has not yet been adequately studied. The current proposal will investigate the
 effects of 2 months of CPAP on energy balance and cardiovascular risk in obese patients with
 OSA. Patients will be instructed to use CPAP at home each night throughout the 2-month
 treatment phases. At baseline and at the conclusion of the 2-month treatment phase, the
 investigators will measure levels of free-living physical activity, sleepiness, sleep
 quality, body composition, cardiovascular risk factors, appetite-regulating hormones, hunger,
 and ad libitum food intake. There will also be a control group with OSA individuals studied
 at baseline and again after 2 months with no CPAP use. It is hypothesized that CPAP compared
 to no treatment treatment will result in improvements in energy balance, including increased
 physical activity, reductions in abnormally high levels of circulating leptin levels, and
 reductions in hunger, food intake, and cardiovascular risk factors. These improvements are
 hypothesized to be associated with increases in the expression of REM sleep and SWS, and
 reduced EDS as a result of CPAP.
This study investigates the effects of 2 mo of continuous positive airway pressure (CPAP) on
 physical activity, energy intake (EI), and cardiovascular risk factors in overweight/obese
 patients with obstructive sleep apnea (OSA).

 Patients will be instructed to use CPAP at home each night throughout the 2 mo treatment
 phase. Before and after the 2 mo treatment phase, patients will undergo a 1-d in-lab testing
 period at the Clinical Research Resource (CRR) at Columbia University Medical Center. Upon
 completion of the laboratory phase 1, patients will return home for a 2 mo treatment period,
 followed by the second tracking period including laboratory visit 2.

 Before and at the conclusion of the 2 mo treatment phase, patients will enter the laboratory
 at the Columbia University Medical Center for a 1-d period. Patients will arrive at ~0800 h
 and will remain in the laboratory for the following 24 h. Blood will be sampled in the
 fasting state in the morning, and will be assayed for select appetite-regulating hormones
 (leptin, ghrelin, adiponectin, glucagon-like peptide-1). We will also assess body
 composition. During the laboratory day, ad libitum EI will be measured for each treatment
 phase. Breakfast, lunch, snack, and dinner will be served at the standard times, but each
 meal item will be served in excess such that patients will be able to eat as much or as
 little of each food as they choose. Additional snack choices will also be freely available
 during the wake episode.

 There will also be a control group of individuals with OSA who do not use CPAP who are
 studied at baseline and again after a 2 month period in procedures similar to those
 undergoing treatment.
Inclusion Criteria:

 -  clinical diagnosis of obstructive sleep apnea (OSA) and excessive daytime sleepiness
 (EDS)

 -  body mass index of at least 25 kg/m^2

 Exclusion Criteria:

 -  prior treatment with CPAP

 -  shift workers

 -  type 2 diabetes

 -  poorly controlled severe hypertension

 -  anemia

 -  history of coronary artery disease, transient ischemic attack, stroke

 -  currently taking anti-psychotic, anti-depressive, or hypnotic medications

 -  females currently taking hormone replacement therapy

 -  females who are pregnant or have given birth within 1 year