 A number of studies have documented poor sleep quality and troublesome symptoms breathlessness, cough and sputum production upon awakening in patients with COPD. However, the investigators know very little about measurements of respiratory mechanics i.e., lung volumes, respiratory pressures, diaphragm function, etc during sleep in these patients. The investigators also know little about how modern bronchodilator therapies, or the timing of when they are taken, affect respiratory mechanics during sleep or the severity of early morning respiratory symptoms. COPD is often treated with inhaled bronchodilator medications which are used to open up airways and make it easier for air to get in and out of the lungs. The investigators are studying the effects of a new inhaler that contains two different types of long-acting bronchodilator: formoterol a long-acting beta2-agonist LABA and aclidinium bromide a long-acting muscarinic antagonist LAMA or anticholinergic. Initial studies have shown that this combination therapy taken twice daily can improve some lung function measurements and respiratory symptoms in patients with moderate to severe COPD. There are also reports that evening administration of this medication may provide important advantages in patients with dominant nighttime and early morning symptoms. It is thought that sustained bronchodilation and lung deflation during the night may improve respiratory mechanics, diaphragmatic function, pulmonary gas exchange, sleep quality, and reduce severity of morning symptoms. This study will be the first to explore the effects of a nighttime dose of aclidiniumformoterol combination therapy on detailed measurements of respiratory mechanics and early morning symptoms in COPD. This study will also give us a better understanding of the mechanisms of early morning respiratory symptoms and their improvement with bronchodilators. 