Determinants of Age Related Breathing Instability During Non-Rapid-Eye-Movement (NREM) Sleep

Inclusion Criteria: * Healthy older and young adults Exclusion Criteria: * Pregnancy, * history of active coronary artery disease-including stable and unstable angina, * recent myocardial infarction, * history of congestive heart failure, * stroke, * excessive daytime sleepiness with Epworth Sleepiness Scale of \>15 * patient with OSA- (Obstructive sleep apnea) on therapy * depression, * schizophrenia, * untreated hypothyroidism, * diabetes on insulin, * seizure disorder, * intrinsic renal and liver disorders, * failure to give informed consent, * patients with evidence of pulmonary diseases based on history and abnormal pulmonary function testing, including obstructive (ratio of predicted forced expiratory volume to forced vital capacity, \<80% predicted) or restrictive lung disorders (total lung capacity \<80% predicted) with resting oxygen saturation of \<96% and kyphoscoliosis (chest wall deformities) * patients on certain medications including, opiates derivatives, stimulants, antidepressants, tranquilizers, anti-psychotic agents, theophylline and other central nervous system altering medications * history of alcohol or recreational drug use will also serve as grounds for exclusion, * patients with body mass index (BMI) \>34kg/m2 * subjects with sleep apnea are already using continuous positive airway pressure for more than 7 days as therapy