Most people do not realize the effect of sleep on breathing at night. People with breathing disorders such as COPD (Chronic Obstructive Pulmonary Disease) and Pulmonary Fibrosis, may have borderline normal levels of oxygen during the day, however, with the onset of sleep, everything changes. The amount of air that your lungs normally hold decreases. The resistance to air flowing in and out of the lungs increases and profound drops in oxygen levels in the body may occur. In addition, with sleep, our corrective responses to these changes are significantly blunted. Sleep Apnea is commonly seen in patients with COPD and extraordinarily common in patients with Pulmonary Fibrosis. The coexistence of Sleep Apnea and these diseases is called the “Overlap Syndrome”. It portends a much worse prognosis and increases the severity of the diseases. Therefore, if you or a loved one have a respiratory disorder accompanied by snoring, excessive sleepiness during the day, moodiness or trouble concentrating, you should be seen by your medical provider or by a sleep specialist to check the possibility of having sleep apnea. Treatment for sleep apnea will positively impact the underlying pulmonary disorder.