Inside Mayo Clinic’s Center for Sleep Medicine (2025)

By Chaunie Brusie, RN, BSN
Inside Mayo Clinic’s Center for Sleep Medicine (1)

Today’s on-the-shelf CPAP masks can be fitted in minutes, but Daniel “Dan” L. Herold, RPSGT, FAAST, can still recall training on the hand-making of plaster nose casts when he first began working at Mayo Clinic’s Center for Sleep Medicine. CPAP masks “had to be glued and strapped onto the nose in the early days. I joined sleep medicine when the first commercial CPAP machines and masks came out, and our supply was limited,” Herold says.

Much has changed from those early days of sleep medicine. Herold, an assistant professor of medicine at Mayo Clinic College of Medicine and a technology and information management specialist at the sleep center in Rochester, Minn, has witnessed much of it in his 43 years with Mayo Clinic.

Since the mid-’80s, Herold has been an integral part of Mayo Clinic sleep center’s evolution from a five-bed unit to where it stands now—a 24-bed facility that’s one of the largest sleep disorders centers in the United States and a leader in training sleep physicians, fellows, and technologists.

Sleep Journey Begins

Inside Mayo Clinic’s Center for Sleep Medicine (2)

Much like the field of sleep medicine has undergone evolution to emerge into a respected subspecialty, Herold’s career has taken unexpected turns to lead him to his current role. His career path is akin to a “Lifetime movie-type thing,” he says, starring a down-on-his-luck college dropout/aspiring musician who gets hired as an animal care tech in research, then an x-ray file clerk to an electrocardiogram (ECG) technician, and then to the sleep lab department at Mayo Clinic.

That sleep lab position offered weekend availability, so he continued his music career. Thanks to knowing his way around a music amplifier (and having a father who had taught him the ins and outs of electronics) and his sleep lab boss and electronics mentor Cameron Harris, RPSGT, Herold quickly became “the guy” known to build and design sleep medicine devices, such as pressure transducers, snoring detectors, and monitors.

A few years in, his skills in critical care, electronics, and sleep studies facilitated his promotion to a lead sleep tech and later supervisor of Mayo Clinic’s Center for Sleep Medicine. “With the advent of digital polygraphs, someone had to learn how these things worked and how to help develop this burgeoning technology,” Herold says. “Needed was how to not only interface existing sleep medicine devices but to develop new ones that fit better in the digital world.” Herold has helped build the sleep laboratory, sometimes quite literally from the machine level up.

“He has been instrumental in the design and development of new technologies for polysomnographic monitoring, enabling advanced techniques to capture any signal essential to sleep studies,” says Kannan Ramar, MD, MBA, director of Mayo Clinic’s Center for Sleep Medicine.

Today, Herold has moved away from hands-on care to working deeply within the data, databases, and technology that’s driving new models of sleep medicine care, while remaining enmeshed in the sleep lab.

“Dan remains a trusted clinical resource, consistently relied upon by colleagues and teams. His extensive experience in the clinical development of sleep medicine—ranging from sleep studies and emerging technologies to IT advancements and research—continues to provide significant value to Mayo Clinic and the broader sleep medicine community,” Ramar says.

Mayo Clinic Model of Sleep Care

Because Mayo Clinic is a tertiary care center with patients traveling from long distances, the team focuses on efficiency, often providing patients with a diagnosis and treatment plan within 48 hours. After an overnight sleep study, reports are ready for morning rounds with the physician, and patients are discussing a care plan with a doctor by 9 am. “We do things like every other sleep lab, but we do it in a different way—what we like to consider the Mayo model of treatment and care,” Herold says.

Mayo Clinic’s Center for Sleep Medicine integrates with other specialties, including pulmonology, neurology, psychiatry, pediatrics, and family medicine. It treats both common sleep conditions and rare and complex disorders. For instance, the clinic offers assessments for central sleep apnea with Cheyne-Stokes respiration and advanced parasomnia studies.

About half the sleep rooms have super high-definition dual-camera setups. As needed, it uses equipment including full electroencephalogram (EEG) and extended electromyography (EMG) to provide additional information about patient activity during sleep.

Additionally, the sleep lab offers advanced therapeutic modalities, such as titrations for volume-assured pressure support and adaptive servo-ventilation.

Training Tomorrow’s Sleep Techs

Inside Mayo Clinic’s Center for Sleep Medicine (3)

Herold is proud of the experts involved in patient care at Mayo Clinic, and he should be—he has helped train many people who work at the sleep lab. “Dan has spent three decades training clinical neurophysiology technologist students in polysomnography and instrumentation, ensuring expertise in the operation of cutting-edge equipment used across the field,” Ramar says.

Herold has been especially influential in shaping the role of sleep techs at Mayo Clinic. All six clinical sleep specialists have a certification in clinical sleep health (CCSH), and there are also 21 polysomnographic technologists (all registered or in training) and 6 polysomnographic technical assistants. “We transformed our laboratory from the norm,” Herold says.

According to Herold, there were only a few formal training programs for sleep techs before the 1990s. But today, Mayo Clinic is heavily focused on educating sleep techs to better care for patients and advance the future of sleep medicine care.

For example, the two-year clinical neurophysiology technologist program through Mayo School of Health Sciences provides training in polysomnography, as well as EEG, EMG, autonomic testing, and nerve conduction, allowing graduates to be board-eligible upon completion. After graduation, those who focused on polysomnography bring a broad knowledge of all areas of clinical neurophysiology to the sleep laboratory.

Mayo Sleep Disorders Center also offers an A-Step program through the American Academy of Sleep Medicine, which provides polysomnography-specific training. “We’re very unique in that we’re a multidisciplinary training program,” Herold says.

After being appointed to faculty from the early days of the clinical neurophysiology technologists program, Herold has continued to be involved by teaching sleep tech students within laboratory rotations and, later, academically. He also guided education from within, serving as secretary, treasurer, and president (chair) of the Board of Registered Polysomnographic Technologists (BRPT). Currently, he is a commissioner for the commission on accreditation of allied health education programs for the BRPT, as well as on the AAST’s continuing education credit accreditation committee.

Dennis Reckward, CCSH, RPSGT, a quality specialist with Mayo Clinic Center for Sleep Medicine, notes that Herold for many years was on the BRPT’s exam development committee, writing and analyzing the RPSGT test questions required for certification. “He is continuously looking at ways to better or advance the practice of sleep medicine for us here,” Reckward says.

Reckward adds that Herold mentors the next generation of sleep professionals and has spent a long time teaching everything from clinical work, electronics, and research to being an invited lecturer at national and international conferences about the work being done at Mayo Clinic. “I’m very passionate about the education portion, and I like teaching—it probably comes from my being on stage as a musician for so long,” Herold admits with a laugh.

(If you’re wondering, Herold is very much still a practicing musician, adept at everything from the keyboard, vocals, guitar, and other stringed instruments. At one point, he even helped start a band comprised of sleep technologists who played at the SLEEP conference.)

Advancing Sleep Care Through Data

Inside Mayo Clinic’s Center for Sleep Medicine (4)

Herold’s work with Mayo Clinic’s Center for Sleep Medicine continues to evolve. He now specializes in the data management groundwork of artificial intelligence (AI) platforms that the clinic is building, as well as data management projects for clinical or research use.

“I’ve changed from managing employees to managing data and searching for new technologies for us,” Herold says. He focuses on new ways to capture and view data, from building databases to structuring interfaces, strategies the center supports by choosing equipment that works with its data goals. Herold explains that some of the center’s guidelines in selecting equipment for the sleep lab include evaluating abilities such as electronic medical record interfacing, data extraction and validation, and AI tools for phenotyping, whether that’s built-in through the equipment or in data collection features for custom models.

He hopes emerging AI platforms will one day detect currently undetected patterns from data to guide diagnoses: “What are we not seeing from the EEG and ECG and other biopotentials and respiratory monitoring? Are there hidden meanings that, in 2050, will be everyday occurrences?”

Herold can see a future that Mayo Clinic sleep information specialists are already working toward, building models that can look at all data to find predictive measures to help better identify comorbidities, such as neurodegenerative, cardiac, or pulmonary diseases. “That’s going to take time and will probably be the norm after I’m long gone, but we’re trying to make that happen,” he says.

Timeframes aside, Herold feels fortunate to continue his career as a pioneer in the sleep medicine space, from the early days of building and designing new styles of sleep laboratory equipment to being at the forefront of emerging technology. “Being on the sleep AI development team here within the sleep laboratory, it’s exciting,” Herold says. “It’s a change in things that I’ve done throughout my career, and I always look back and see how lucky I’ve been to be here with such great people and to be part of what I feel is the cutting-edge of sleep technology. Data mining and extracting data can be very arduous and time-consuming but extremely valuable for discoveries.

“I’m very proud to be working for this great place and how we help people and making sure we always keep in mind the Mayo model of care primary value: the needs of the patient come first. We’re always working towards innovation, always.”

Top photo: Daniel “Dan” L. Herold, RPSGT, FAAST (center),Dennis Reckward, CCSH, RPSGT (left), and Chris Fenske, CCSH, RPSGT, consult with each other at Mayo Clinic.

Photography by Nathan Parker/Mayo Clinic

Learn more about the evolution of sleep medicine:

Inside Mayo Clinic’s Center for Sleep Medicine (2025)

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