Sleep Center at Comprehensive Helps You Sleep Better.
Sleep Center at Comprehensive is a full-service sleep disorders center in Nevada. We have four Board Certified Sleep Medicine physicians on staff as well as a highly trained team of technicians to evaluate, diagnose and treat patients with sleep disorders. We provide compassionate care, focusing on the needs and concerns of the patient to provide the highest quality of service. We are the only sleep center in Nevada to continually adjust patient’s CPAP machines to ensure their treatment remains comfortable and effective.
- Sleep disorders
- Shift Work Disorder
- Restless Leg Syndrome (RLS)
- Insomnia
- Nocturnal seizures
- Sleep Apnea
- Behavioral Sleep Medicine
- CPAP Management and Adjustment
- Dental Sleep Medicine
- Diagnostic Testing
- Pulse Oximetry
- Sleep Study
Our Team of Doctors.

Nisarg Changawala, MD, MPH
Dr. Changawala treats patients with lung disease and sleep disorders including asthma, emphysema, chronic bronchitis, chronic cough, nicotine dependence, snoring, insomnia and sleep apnea

John (Jack) Collier, MD, FCCP, DABS
Dr. Collier treats patients with lung disease and sleep disorders including asthma, emphysema, chronic bronchitis, chronic cough, nicotine dependence, snoring, insomnia and obstructive sleep apnea

James S. J. Hsu, MD, FCCP, DABSM
Dr. Hsu treats patients with lung disease and sleep disorders including asthma, emphysema, chronic bronchitis, chronic cough, nicotine dependence, snoring, insomnia and obstructive sleep apnea.

Ralph Nietrzeba, MD, FCCP, FACP
Dr. Nietrzeba treats patients with lung disease and sleep disorders including asthma, emphysema, chronic bronchitis, chronic cough, nicotine dependence, snoring and obstructive sleep apnea.

George Tu, MD, FCCP, DABSM
Dr. Tu treats patients with lung disease and sleep disorders including asthma, emphysema, chronic bronchitis, chronic cough, nicotine dependence, snoring, insomnia and obstructive sleep apnea.

John J. Wojcik, MD, FCCP, DABSM
Dr. Wojcik is board certified in Pulmonary Medicine and Sleep Medicine. He is a Fellow of the College of Chest Physicians. He has been in practice since 1997.