Our Professional Staff

The Best in Sleep Disorder Therapy

Meagan Rizzo, MD

Meagan Rizzo, MD joined us in November 2024, bringing with her 20 years of experience as an Army physician, specializing in sleep medicine.
Most recently, Dr. Rizzo was the Chief of the Sleep Disorder Center at Walter Reed National Military Medical Center, where she served active duty, retirees, and dependents of all ages.
She also served in the prestigious role as a Specialty Consultant to the White House Medical Unit while at WRNMMC, where she was the sole sleep provider for senior government leaders.
When she’s not working, Dr. Rizzo enjoys spending time with her husband and their four children. Dr. Rizzo has always been committed to fitness. In her free time you can find her in the pool, on a bike, or on the run. She has completed two half iron man races and countless other triathlons.

Dr. Emsellem has actively promoted sleep disorders awareness and the need for sleep education locally and nationally, acting as a go-to media resource for the National Sleep Foundation (NSF) and a spokesperson for the recent Sleep in America Polls sponsored by the NSF. She was a key member of the NSF committee establishing the National Sleep Foundation’s Teen Sleep Awareness Program and was a featured speaker at the June 2005 meeting of the Association of Professional Sleep Societies, presenting in the National Sleep Foundation’s symposium “Adolescent Sleep and School Start Times.” Dr. Emsellem has also presented talks on “Sleep and Adolescents,” “The Physiology of Sleep in Adolescents,” and “What Is Normal for Sleep in Adolescents?” She has been the keynote speaker on sleep issues at such conferences as the National Youth Leadership Forum on Medicine and the American Association for the Advancement of Science. Dr. Emsellem has been featured as a sleep expert on “Medical Answers,” a syndicated PBS television show; “Doc in the House,” a syndicated radio call-in show; “ABC Now,” a cable program; and “Girl Talk,” a live radio call-in show in the Washington, D.C., area. She is also quoted regularly in columns and articles in national publications covering health and sleep, including Redbook, Glamour, U.S. News & World Report, Scientific American, the Washington Post, Washingtonian Magazine, MORE Magazine, Cosmopolitan, Weight Watchers Magazine and the AARP Bulletin.

In addition to appearing on radio and television shows, sharing her expertise through various publications and direct presentations, teaching and seeing patients, Dr. Emsellem has been the principal investigator in numerous national studies of investigational agents for the treatment of sleep disorders. She has also authored many articles and book chapters and her writing has appeared in publications such as Sleep, Sleep Research, and the Report of the National Commission on Sleep Disorders Research. Dr. Emsellem has been named to the Washington, D.C., area’s Consumer’s Checklist of Top Doctors and Washingtonian Magazine’s Top Doctors guide.

Dr. Emsellem has a great love for patient care, teaching and a long-standing interest in Sleep Disorders Medicine. After graduating from the George Washington University (GWU) School of Medicine she completed a rotating internship that included Psychiatry, Internal Medicine and Neurology. She was intrigued with the complexity of brain function and decided to pursue a career in Neurology. She completed her Neurology residency training at GWU and sub-specialty training in Epileptology and Clinical Neurophysiology at Johns Hopkins University. She then returned to GWU in an academic career track in the Department of Neurology. Over the ensuing 11 years she enjoyed her role as an academic Neurologist with patient care responsibilities and as the Neurology Residency Training Program Director, Director of the EEG Laboratory and Director of the Neurology medical student teaching program and established the Sleep Laboratory at GW, the second at the time in Washington, DC. Her academic career blossomed and she was promoted to Associate Clinical Professor of Neurology and won student teaching awards. She is a member of the medical honor society Alpha Omega Alpha. During her final year at GWU Dr. Emsellem was the Acting Chairman of the Department of Neurology. Today Dr. Emsellem continues to play an active role teaching at GWU in the medical school neurology curriculum, preceptoring Neurology Residents, Physician Assistant and Nurse Practitioner students who rotate through her office as part of their training, and lecturing nationally on topics in Sleep Medicine.

In 1995, after leaving academia to focus more on direct patient care, Dr. Emsellem established The Center for Sleep & Wake Disorders of Chevy Chase which has grown into a full service, 11-bed sleep disorders center addressing the patient care, research and educational needs of our community. Dr. Emsellem has a passion for running her practice, an endeavor she finds both exciting and challenging. She loves teaching and is a firm believer in managing health through patient education and challenges her patients to be active, knowledgeable participants in their healthcare. She is committed to the advancement of the field of sleep medicine and is actively involved in clinical research in many areas of sleep medicine including excessive daytime sleepiness, narcolepsy, restless leg syndrome, obstructive sleep apnea, shift work sleep disorders, insomnia and pediatric and adolescent sleep disorders.

In her leisure time Dr. Emsellem enjoys sailing, skiing and traveling with her husband, David and their three daughters. She is an avid road cyclist and has completed the AIDS bike ride, supporting Food and Friends, biking from Raleigh, North Carolina to Washington, DC as a community service and bonding experience together with her eldest daughter Stella. With colleagues from The Center for Sleep & Wake Disorders and friends she established The Dream Team, riding for fun and exercise and taking on cycling challenges for good causes in the Washington, DC area.

For more detailed information regarding Dr. Emsellem’s professional career, please review her complete Curriculum Vitae.

Professional Staff

Linda Croom, ANP-C

Linda Croom (pronouns: she/her) joined The Center for Sleep & Wake Disorders in 1998. Linda graduated from Mary Washington College with a BS in Biology and obtained her BS in Nursing from George Mason University. She worked at Virginia Hospital Center (Arlington Hospital) for ten years in medical-surgical nursing, advancing to the position of head nurse. Linda’s interest in the delivery of direct patient care led her to return to school, completing her Masters degree in Nursing from George Mason University and Nurse Practitioner requirements in collaboration with the George Washington University. As a Nurse Practitioner Linda worked for 3 years in a busy internal medicine practice in Fairfax, Virginia before her desire to specialize came to fruition when she joined Dr. Emsellem and The Center for Sleep & Wake Disorders. Linda has found that working as a Nurse Practitioner in Sleep Medicine is continually challenging and very rewarding. Linda brings a warm, caring style to the practice and is gratified by the high percentage of patients who experience a major improvement in quality of life when their sleep disorders are treated. Linda has been actively involved in our research efforts studying investigational treatments for sleep disorders. She has been the Study Coordinator for several research protocols, assisted in the training of our current research staff and has functioned as a sub-Investigator on many studies. In her spare time, Linda enjoys raising her son, gardening, biking, swimming, and dinner parties.

Stevie Carter, PA-C

Stevie Carter, PA-C left our practice as of March 5, 2021, in order to take a position with a vaccine development company. We are sad to see her go, but wish her the best in her new endeavors.

Danielle Mandir, PA-C MPAS

Danielle Mandir (pronouns: she/her) joined The Center for Sleep & Wake Disorders as a Physician Assistant in October of 2018. Danielle graduated from Tulane University with a Bachelor of Science in Public Health. She attended Wake Forest School of Medicine and graduated with a Master’s Degree of Physician Assistant Studies. After school she decided to move back home to Washington D.C. and start her career in the fascinating field of sleep medicine. Danielle believes in creating a positive patient-provider relationship in order to deliver the highest quality of patient care. In her spare time she enjoys traveling, playing tennis, and spending time with her friends and family.

Keta Porter

Keta Porter (pronouns: she/her) joined The Center for Sleep & Wake Disorders in April 2019. She graduated from Bryn Mawr College with a Bachelor’s in Mathematics. Her future plans include becoming a healthcare provider or administrator. In her spare time, she likes to go on long walks, spend time with family and friends, and listen to Reggae music.

Billing Department

Lisa Adon

Lisa Adon began working as Billing Specialist at The Center for Sleep & Wake Disorders in 2001. Before joining our team she was the Billing Manager at a 10-physician primary care clinic. Lisa is organized, methodical, and extremely experienced in dealing with insurance companies and patients to ensure the efficiency of the billing process. Lisa enjoys spending time with her family and traveling to warm places!

Robyn Allyson

Robyn Allyson began working as a billing assistant for The Center for Sleep & Wake Disorders in 2015, and also worked at the front desk in 2005. Before joining the “Dream Team”, she owned and operated a fine art business in Bethesda, for many years. She loves to cook, travel, and has a passion for classic cars.

Sleep Lab

Matthew Henning, RPSGT

Matt has worked as a Sleep Technologist at The Center for Sleep & Wake Disorders since 2012, and has been the lab manager since 2020. Working mostly at nights, Matthew has enjoyed his time helping patients feel at ease in the lab setting as well as assisting in treatment for various sleep disorders. He has a special interest in helping patients newly diagnosed with obstructive sleep apnea, striving to achieve the best results from therapies such as Positive Airway Pressure (PAP). He considers himself a “sleep enthusiast” and likes to stay current with the latest technological advancements in sleep testing. His goal in sleep medicine is to provide excellent technical diagnostic care to patients in the least invasive setting possible. Matthew enjoys cooking, chess and is a loyal supporter of many sports teams.

Front Desk/Administrative Support Staff

Diane Graham Merkel

Diane (pronouns: she/her) has been the office manager for the Center for Sleep & Wake Disorders since January 2019. She attended Prince George’s Community College and the University of Maryland. She has worked in the medical field for over 45 years. Diane’s favorite pastimes are spending time with family, with her dogs: Tinker, Bosco, and Butter, as well as traveling to different parts of the country.

Contact The Center For Sleep & Wake Disorders

5454 Wisconsin Ave., Suite 1335

Chevy Chase, MD 20815

Phone: 301-654-1575

Fax: 301-654-5658

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Need some guidance and general information? Check out our comprehensive information and useful links page that covers everything from what is a “good night’s sleep” to links to sleep-related organizations around the world.

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