How Penn’s Sleep Center has changed the world of sleep in the past 25 years
Sleep: Giraffes require less than 2 hours a day while brown bats need almost 20. Humans fall about in the middle, needing between seven to eight hours every day. But, whatever the amount, we now know that it’s a requirement for life.
But this was not common knowledge in the 1970s when the three people credited with bringing the Penn Center for Sleep and Circadian Neurobiology to fruition -- David Dinges, PhD; Allan Pack, MBChB, PhD; and Adrian Morrison, DVM, PhD – were researching this relatively unknown area. Dinges, who is chief of Sleep and Chronobiology in Psychiatry, was studying how sleep deprivation in healthy humans affected safety and health. Morrison, director of the Laboratory for the Study of the Brain in Sleep at Penn’s School of Veterinary Medicine, was investigating what regulated sleep in animals, specifically bulldogs (who can suffer from sleep apnea because of its short snout and underbite). And Pack, chief of Sleep Medicine, was studying the nature of sleep apnea and performing sleep studies at HUP.
By the mid-80s, the three researchers were interacting and collaborating… and realizing that sleep was “far more important than people realized,” Dinges said. Working together also brought another recognition: Sleep didn’t belong to any one area of study. It was interdisciplinary. “Sleep defied the way in which scientific funding organized problems,” Dinges said. “It was clear that sleep cut across fundamental questions.”
Penn’s multidisciplinary approach to studying sleep was unique at the time. It was the first such university-wide sleep center in the United States. And when Penn created an independent Sleep Medicine division in 2001, this too was a first. In a 2006 report by the Institute of Medicine entitled “Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem,” the committee recommended that Penn’s comprehensive center model for sleep be implemented in all major academic medical centers.
Over the years, the Sleep Center has served as a springboard for a wide range of investigative work unlocking the secrets of sleep – starting at the molecular, genetic level – and its impact on all living organisms. “The Center gave our work an identity, an organizational structure in which to interact in all problems related to sleep,” Dinges said.
From Research to Public Policy
When the Center was created, REM (rapid eye movement) was a well-known phenomenon, but the basics of sleep – why do we do it? why do we need it? – remained unknown. “This was a fantastic opportunity, a wide-open field,” Pack said.
Many milestones followed. In the mid-1990s, Pack, Joan Hendricks, VMD, PhD (now dean of Penn’s School of Veterinary Medicine), Amita Seghal, PhD, director of the Chronobiology Program, and sleep research colleagues yielded new insight into the genetic basis of sleep in fruit flies and how internal clocks (circadian rhythm) govern sleeping and wakefulness. Later studies proved a similar circadian rhythm controlled sleep in humans – and all other living organisms --as well.
Dinges continued to study the impacts of sleep deprivation, introducing the Psychomotor Vigilance Test (PVT) and other testing measures to study effects of fatigue on cognitive and motor responses. As he noted in 2012 in Penn Medicine (the alumni magazine for the Perelman School of Medicine), “We’re interested in what lifestyle stressors – like not getting enough sleep, or being awake at night like a nightshift worker, or traveling across time zones, or not getting enough sleep and getting exposed to a stressful situation – do to people’s ability to function, emotionally, behaviorally, cognitively, performance-wise.”
This research helped shape public policy regulating safety-sensitive shift work (such as health-care professionals and commercial truck drivers). It also expanded our understanding of human behavior and performance in space flight. NASA used specially tailored PVT (and other test measures) in the Columbia Space Shuttle mission, John Glenn’s return to space, and most recently, Scott Kelly’s year-long orbit in space aboard the international space station, which laid the groundwork for a potential future mission to Mars.
Building a Sleep Center Network
Sleep disorders were still relatively unknown to community primary care practices in the 1990s. Pack wanted to change that. “We came to realize just how common sleep disorders were– especially sleep apnea— and how we could help people,” he said.
Partnering with Penn’s primary care networks -- Clinical Care Associates and Clinical Health Care Associates – Pack embedded sleep experts in the practices, providing easy access for patients. Over the course of seven years, he built a network of sleep labs, expanding his first four-bed lab in HUP to 26 beds throughout the region. His lab’s clinical studies to better understand sleep apnea, its consequences and prevalence led to developing a screening tool -- the MAP (multivariable apnea prediction index) questionnaire -- which measures a patient’s relative risk of getting apnea. The tool is now used nationally and in other countries around the world. Pack and his colleagues also developed the standard for compliance in using CPAP therapy. His basic research in sleep apnea – including an understanding of the biological mechanism that leads to the disease – raised its profile in the scientific community and in the general public.
The majority of sleep studies are still performed in sleep center labs –especially when it’s a symptom of heart disease or other serious disorders – but Pack knew years ago that home studies were the wave of the future. His insight led the way to Penn’s pioneering sleep telemedicine efforts for home monitoring, allowing providers to easily access information remotely.
What is the future of sleep at Penn? New areas of focus include the role sleep loss plays in progressing neurodegenerative brain diseases, such as Alzheimer’s; how sleep disorders can be a risk factor for different cancers; and the relationship between sleep and metabolism. These partnerships demonstrate once again how far-reaching sleep’s impact can be.
“This is so characteristic of the sleep field,” Dinges said. “As soon as we look at a new area, we realize sleep has a role. It influences a great many systems … In terms of priorities in the public health sector, it’s right up there with nutrition and exercise.”
Yet the mystery of sleep remains. “I’m still obsessed with the problems we set up to answer or solve 30 years ago!” Dinges said, laughing. But “it’s been a positive experience to see the growth of the field and how many we trained and are now successful themselves.” Indeed, all of the speakers and chairs of the sessions at last month’s one-day symposium celebrating the Center’s 25th anniversary did training in sleep/circadian research at the Penn Sleep Center.
“We got the ball rolling,” Dinges continued, “focusing the full power of science on a really fundamental, biological question to all life on earth.”
(Top) PhD candidate Issac Perron works with mentors Sigrid Veasey, PhD, and Alan Pack, MD, in studying how poor diet and weight gain contribute to excessive sleepiness in mice.
(Middle) David Dinges has worked with NASA on a variety of studies for more than 20 years.
(Bottom) Robert Warrell, chief technologist in Sleep & Respiratory Neurobiology, watches the brain wave patterns and other bio functions of a patient undergoing a sleep study.