The Night Chicago Started Waking Sleepers on Purpose

REM sleep was identified by Eugene Aserinsky and Nathaniel Kleitman at the University of Chicago, reported in Science on September 4, 1953, and tied to dreaming by deliberate awakenings, most systematically in William Dement and Kleitman’s 1957 study. The first subject was Aserinsky’s eight-year-old son. In December 1951, as Smithsonian magazine tells it, Aserinsky sat the boy, Armond, on an Army cot at the University of Chicago, scrubbed the boy’s scalp, taped electrodes to his head and went to watch the paper unspool. The pens tracking the boy’s eyes were swinging back and forth as though Armond were wide awake and looking around the room. Aserinsky walked in to check and found the child’s eyes shut. Armond was asleep.

A pen swinging on graph paper told Aserinsky that something was happening. It could not tell him what. The answer came from a cruder idea that the field still depends on: wake the sleeper at that moment and ask.

What Aserinsky was supposed to be doing

Aserinsky was a graduate student in physiology working under Nathaniel Kleitman, who had run sleep research at Chicago for decades. The University of Chicago credits Kleitman with opening the first laboratory in the country devoted entirely to sleep, in 1925. The assignment Kleitman gave Aserinsky was modest: study behavioral signs of falling asleep, with infants as subjects. Aserinsky noticed substantial eye movements in sleeping babies, and that led him to try recording them electrically.

Hence the equipment on that December night. The recording machine was something Aserinsky hauled up from a basement at the university, and the eye channel was a trial of an electrooculogram, electrodes placed near the eyes so that each flick of the eyeball would move a pen. His son was a convenient volunteer. By the end of that session Aserinsky had a puzzle: the eyes of a sleeping child were moving the way an awake person’s eyes move when scanning a scene.

He did not publish on the strength of a puzzle. He ran adults, night after night.

The measurement that required an interruption

Here is the claim this piece will defend: the discovery of REM sleep was not made by watching sleep. It was made by interrupting it. Eye movements by themselves were an odd curiosity. What turned them into a window on dreaming was a procedure in which researchers deliberately ended a sleeper’s night, repeatedly, at chosen moments, and then asked a question.

The reasoning was simple enough to state. The eyes moved as if scanning. A scanning eye suggests something to scan. So rouse the person and ask what they were looking at. Psychiatric News, in its fiftieth-anniversary article, gives the sequence: the researchers saw the heart beat faster and breathing quicken when the eye movements occurred, signs of arousal, and then roused sleepers.

The paper describes 20 adult sleepers; the dream interviews covered a subset of them. In that subset, per Psychiatric News, 10 subjects were questioned after 27 REM episodes and gave 20 dream reports (about 74 percent). The same subjects were questioned 23 times while the eyes were still, and 19 of those awakenings produced no dream recall. The contrast was the discovery. A dream detector, built from a pen, a pair of electrodes and a person willing to be woken, had worked — crudely, but it had worked.

The paper itself was short. Published in Science on September 4, 1953, under the title “Regularly occurring periods of eye motility, and concomitant phenomena, during sleep,” it ran about a page and a half. In that space it reported that the periods recurred several times a night, that they came with faster breathing and more body movement, and that the sleepers woken from them usually had vivid visual dreams to describe.

What the two men did not have, in 1953, was a name or a clean theory. The label rapid eye movement sleep, and the later insight that the sleeping brain in those periods is highly active, came afterward. The 1953 paper is better read as a first, careful count of a pattern in the dark than as a finished account of dreaming.

The medical student who disagreed with both of them

A different kind of person entered the lab in the fall of 1952. William Dement was a second-year medical student at Chicago who planned a career in psychiatry. Kleitman assigned him to help Aserinsky with overnight sessions, and the pair reportedly filmed sleepers in REM on 16-millimeter film.

Dement’s motives were different from his seniors’. In an interview quoted by Psychiatric News for the fiftieth anniversary, Dement said: “Aserinsky and Kleitman sneered at Freud. I thought Freud was God.” For a young man who wanted to understand dreams, a method that flagged when a sleeper was probably dreaming had an obvious appeal. It meant that dream content could be collected on demand rather than hoped for over breakfast.

That is the thread from 1953 to 1957. In the Dement and Kleitman paper, “The relation of eye movements during sleep to dream activity: an objective method for the study of dreaming,” the awakening procedure became a protocol. Nine adult volunteers took part, seven men and two women, in the usual summaries of the study; five were studied in detail and four mainly served to confirm the others. The volunteers were woken during the night by a doorbell, spoke into a tape recorder about what they had been dreaming, if anything, and went back to sleep. The experimenters stayed out of the room during recall.

The tally from that work is the one students memorize. Dreams were reported in 152 of 191 awakenings from REM periods, and in 11 of 160 awakenings from non-REM sleep.

Notice what the doorbell is doing here. In the 1953 paper the awakening confirmed a hunch. By 1957 it had become the instrument. Nobody could read a dream off a graph, so the experiment was built from a graph that said “now” and a bell that cut the night short.

Three studies that are easy to blur

Popular accounts tend to merge these three pieces of work, and they answered different questions.

Aserinsky and Kleitman (1953, Science) established that periodic bursts of eye movement, faster breathing and body motion occur in sleep, and that waking people during them mostly produced dream reports. The question was whether there was a recurring state at all.

Dement and Kleitman (1957) asked whether the state tracked dreaming closely enough to be used as a tool. They compared REM and non-REM awakenings with a fixed procedure, and the recall gap was large.

Dement (1960, Science, volume 131) went on to ask what happens if the dreaming state is prevented. He woke volunteers at the onset of each REM period for five successive nights. The awakenings needed per night grew, and afterward the volunteers spent far more of undisturbed sleep in REM. That result is the origin of the idea of REM rebound, which this site covers in its explainer on what happens after REM loss.

A related Dement experiment, with Edward Wolpert in 1958, tried an inverse question: do sounds, light and water on the skin leak into dreams? Later reviews summarize its results as water appearing in about 42 percent of dream reports, light flashes in 23 percent and tones in 9 percent, a finding this site has used in its piece on dreaming that you turned off the alarm.

What a bell did that watching could not

A graph records what a body does. A dream is what a person says happened, and the only way to get it is to ask while the memory is fresh. That is why the awakening could not be skipped, and why the timing mattered: a sleeper woken in the middle of an eye-movement burst has the dream still in hand, while one woken from quiet sleep usually has nothing to report. The 1953 and 1957 tallies are two versions of the same observation, and the gap between them and the quiet-sleep counts is what made the bell an instrument rather than an annoyance.

Every central finding that rests on dream reports, from the REM and non-REM split to the deprivation work, was assembled by researchers interrupting people at moments they chose. Without the arousal there are eye movements and a pen; with it there is a psychology of dreaming.

That does not make being woken good for anyone. The volunteers woke to a doorbell they expected and went back to sleep in a lab, and Dement’s 1960 volunteers reported anxiety and irritability after repeated interruption of REM. The narrower point is historical: the first people deliberately woken at a precise moment of the night for the sake of knowledge were Kleitman’s sleepers, and the method they used is still how researchers connect what a sleeper’s body does to what a sleeper reports.

Who gets named

Credit for the discovery has been contested. Aserinsky later wrote that Kleitman had a peripheral part in the specific study, and a 2024 article in Sleep titled “Who discovered REM sleep?” takes up the question. Aserinsky took his Ph.D. in 1953 and left Chicago. Kleitman, who had been building the field since the 1920s and had spent decades on circadian questions, including the 1938 Mammoth Cave experiment described in a piece on people who lived without clocks, is usually credited with the laboratory, the question and the supervision. Aserinsky is credited with the sighting and the first adult recordings, and Dement with turning the awakening into a repeatable method. The 1953 paper carries two names, Aserinsky’s first.