While the field of modern sleep medicine is little more than a century old, scientists have made considerable strides in understanding what happens inside our bodies and brains after we doze off, as well as the roots of, and remedies for, rest-gone-awry. During a 60-year period beginning in the mid-20th century, the formerly non-existent discipline became a global priority. Experts codified sleep disorder diagnoses, standardized ways to measure how and how well people sleep, and generally chipped away at lingering questions regarding the role of sleep in physical and mental well-being. In the past decade, public health officials have declared sleep deprivation a full-blown epidemic and researchers have doubled down on efforts to untangle the physiological, genetic and environmental roots of sleep disorders.
Today, sleep is a dynamic interdisciplinary field, heightened by contributions from psychiatrists, neurobiologists, pulmonologists and neurologists, among other scientists and physicians. Given the breadth of the field, the number of sleep milestones runs high, but here are some of the most revolutionary breakthroughs in sleep research.
Henri Pieron, a French psychologist, published a book called Le Probleme Physiologique Du Sommeil, the first physiological examination of sleep. Pieron’s text is officially regarded as the start of modern sleep research.
German psychiatrist Hans Berger first recorded human electrical brain waves and noted differences between activity patterns in the sleeping and waking brain.
Nathaniel Kleitman, a physiology professor at the University of Chicago who’d earn the nickname the “father of modern sleep research,” discovered REM sleep, and (correctly) hypothesized a link between the high-activity sleep stage and vivid dreaming.
Stanford University Psychiatrist William C. Dement, the “father of sleep medicine,” teamed up with Kleitman, his former teacher, and created a sleep-stage classification system involving REM sleep and four stages of NREM sleep. Barring a few tweaks, the classification system remains in use today. (Dement would also define sleep medicine as “the branch of medicine that deals with the sleeping brain and all manifestations and pathologies deriving therefrom.”)
French researchers Gastaut and Broughton distinguished parasomnia (sleep arousal disorder) episodes, which occur during slow-wave sleep, from epileptic episodes. Soon after, the team established defining characteristics of parasomnia episodes, including amnesia and indifference to one's environment.
Dement established the Stanford Sleep Clinic, the country’s first full-scale sleep research center. This would pave the way for the creation of more than 1000 sleep clinics now in operation across the country.
Stanford researchers found narcolepsy in two Doberman Pinschers, prompting the establishment of a narcoleptic canine colony that fueled progress in understanding the physiological basis of the debilitating disorder.
Dick Bootzin, then a Northwestern psychologist, floated an evidence-based theory of insomnia as a product of one's sleeping environment, and developed the first non-pharmacological treatment technique, called Stimulus Control, which became a critical component of CBT (cognitive behavioral therapy).
Australian physician Colin Sullivan invented the Continuous Positive Airway Pressure (CPAP) machine to treat sleep apnea. Previously, doctors used more radical methods, including tracheotomy.
Carlos Schenck and Mark Mahowald identified and named REM Behavior Disorder (RBD), in which a failure of skeletal-muscle paralysis during REM sleep causes people to act out their dreams.
University of Chicago psychiatrists found that rats died from sleep deprivation within two-to-three weeks.
A year after studies showed that narcoleptic dogs and mice have mutations in hypocretin, a wakefulness-promoting brain chemical, Stanford researcher Emmanuel Mignot linked hypocretin deficiency with one type of narcolepsy (narcolepsy cataplexy) in humans.
Scientists at the University of Utah discovered the first human clock genes while studying familial advanced sleep phase syndrome, a rare genetic disorder that makes people fall asleep early and wake up spontaneously throughout the night.
A University of Wisconsin research team found a high mortality risk associated with sleep-disordered breathing. Elsewhere, researchers used epidemiological data to link sleep deprivation with obesity and diabetes. The last decade has seen the emergence of sleep as a public health concern, with an increasing focus on the connection between poor sleep quality, chronic disease and socioeconomic factors.
In one of a stream of studies helping scientists inch closer towards understanding the purpose of sleep (still a mystery), Washington State University neuroscientists observed sleeping-state EEG patterns in a petri dish of neurons, suggesting the neurons independently fell asleep and challenging the idea of sleep as a whole-brain phenomenon.