From Asclepius to MIT: choosing what to dream

Long before sleep laboratories, there were sanctuaries. For centuries, people in the Greek world travelled to the sanctuaries of Asclepius, the god of healing, to sleep in a sacred place and wait for a dream. The practice is called dream incubation, and the idea behind it is surprisingly modern: what you hold in mind as you fall asleep may shape what you dream.

Sleeping in the sanctuary

Incubation, from a Latin word for lying down in a place, is the practice of sleeping at a god’s sanctuary to receive a healing or guiding dream. It appears across the ancient world, with roots in Near Eastern sources and Pharaonic Egypt, but it is most closely tied to Asclepius.^[2]

At his sanctuaries, the most famous being Epidaurus in the Peloponnese, people seeking a cure slept in a special hall called the abaton and hoped the god would come to them in a dream, either to heal them or to tell them what to do. Stone tablets set up at Epidaurus recorded dozens of such cures, from the plausible to the miraculous. Emma and Ludwig Edelstein’s classic 1945 collection gathers the ancient testimonies about the god, his cult and his temples, in the original languages and in translation.^[1]

These accounts are not medical records. They were set up by the sanctuary, for visitors, and scholars debate how much of them describes real events. What they do show is how seriously ancient people took two ideas: that sleep could be prepared for, and that a dream could be invited. You can read a short version in the Atlas entry on Asclepius, alongside other night traditions.

The committee of sleep

In the early 1990s, Deirdre Barrett, a psychologist at Harvard Medical School, tested a modern version. Seventy-six college students taking a class on dreams each chose a problem, personal or academic, that had a recognisable solution, and focused on it at bedtime every night for a week. About half recalled a dream they judged to be related to their problem, and most of those believed the dream contained a solution. Independent judges rated slightly fewer dreams as addressing or solving the problem than the dreamers did, though the trends were similar. Personal problems were much more often judged solved than academic ones.^[3]

It was a homework assignment, the students were already interested in dreams, and there was no comparison group of people who did not incubate, so the study shows that incubation is possible, not how well it works.^{[3, 5]}

A wearable at the edge of sleep

In 2020, Adam Haar Horowitz and colleagues at the MIT Media Lab, working with the sleep researcher Robert Stickgold, described Dormio, a wearable device for what they called targeted dream incubation. Rather than relying on willpower, it watches for signs of sleep onset, the drowsy, image-filled stage sometimes called hypnagogia, and plays a recorded prompt at that moment, so that the theme is repeatedly presented as the person drifts off.^[4] It tracks signals such as heart rate, skin conductance and muscle tone, then wakes the sleeper briefly to record a dream report, and the cycle repeats.^[5]

A controlled experiment followed in 2023. Forty-nine adults took part in a 45-minute afternoon session and were randomly assigned to four groups: napping or staying awake, and either hearing the prompt “remember to think of a tree” or simply being asked to observe their thoughts. In the napping group with the tree prompt, an average of 70.3% of each person’s dream reports mentioned a tree, compared with 1.4% in the napping group without it. Afterwards, everyone completed three creativity tasks themed around trees. The napping group with the tree prompt scored highest on an overall creativity measure, outperforming each of the other three groups, and more references to trees in people’s reports went with higher scores.^[5]

The authors are clear about the limits: groups of about a dozen people, a single theme, creativity measured only straight afterwards, tasks always given in the same order, and no EEG to confirm the exact stage of sleep. They describe it as the first controlled experiment of its kind, which makes it a promising start rather than a settled finding.^[5]

What incubation can and cannot do

Taken together, the evidence suggests that what you focus on as you drift off can sometimes show up in your dreams, and that this may occasionally help with creative or personal problems. It is exploratory: a few small studies, often with self-rated outcomes. It does not show that dreams carry hidden messages, and nothing about incubation lets a dream predict the future.

It is also not a nightmare treatment. For recurring nightmares, the method with real evidence is imagery rehearsal, which changes the dream while you are awake and rehearses the new version. Our guide to stopping nightmares is the place to start.

If you would like to try it

1. Choose something light. A place you love, a person you miss, a question you are curious about. Leave distressing themes out of it.
2. Keep it short. Write it in one line, and read it once before bed.
3. Hold it gently as you drift off. Picture it for a minute or two, then let it go. Trying hard keeps you awake.
4. Check in the morning, kindly. Note whether anything showed up, even in a changed form.
5. Expect misses. On many nights the theme will not appear, and that is fine.

This is the spirit of Baku’s “tonight’s intention”: choose what you would like to dream about, and in the morning answer one playful question, did it show up? It is a small experiment, not a therapy, and the visitors to Epidaurus might well have recognised it.