Lucid dreaming

What it is

Knowing that you are dreaming, while you are dreaming — and, in the fuller form, being able to direct what happens next.

Roughly half of people report having had at least one lucid dream; around a quarter have them monthly or more; a small proportion have them frequently and can induce them at will.

Where it came from

Reports are old. Aristotle mentions the awareness that one is dreaming. Tibetan Buddhism has a formal practice — milam, dream yoga, one of the six yogas of Nāropa — treating the recognition that one is dreaming as training for recognising the constructed nature of waking experience, and ultimately for the bardo states after death. It is described under Tibetan practice.

The Dutch psychiatrist Frederik van Eeden coined "lucid dream" in 1913.

And then it was proved, which is the important part.

The problem was structural: a dream is a private experience reported after waking, so no amount of testimony establishes that anyone was conscious during it rather than confabulating afterwards.

The solution was elegant. Skeletal muscles are paralysed during REM sleep — but the eye muscles are not.

In 1975 Keith Hearne, working at the University of Hull, arranged with an experienced lucid dreamer, Alan Worsley, that on becoming lucid he would move his eyes left and right in an agreed pattern. The signal arrived, recorded on the electro-oculogram, from a subject whose EEG confirmed he was in REM sleep.

Stephen LaBerge at Stanford established the same result independently and published it, and the technique became the field's standard. Lucid dreaming moved from anecdote to laboratory measurement, and it is now ordinary sleep science.

In 2021 it went further. Konkoly and colleagues, publishing in Current Biology across four independent laboratories, established two-way communication with sleeping lucid dreamers: experimenters asked spoken questions, including simple arithmetic, and received correct answers via eye-movement codes, from people who were verifiably asleep.

That is a genuinely remarkable result, and it is worth pausing on: someone was asked a maths question while asleep and dreaming, worked it out inside the dream, and answered.

How it is done

The main induction methods are documented, and this article names them without instructing: reality-testing during the day, waking after several hours of sleep and returning to bed with the intention of recognising a dream, and LaBerge's mnemonic technique of rehearsing that intention while falling asleep.

Galantamine, an acetylcholinesterase inhibitor used clinically in Alzheimer's disease, has been shown in a controlled trial to increase lucid dream frequency substantially. It is a real drug with real effects and interactions, and it is mentioned here as a research finding rather than a suggestion.

What we can and cannot say

We can say lucid dreaming is established beyond dispute, which distinguishes it from everything else in this section. It is measurable, inducible, replicable across laboratories, and has an identified neural signature — increased frontal activity in regions normally quiet during REM, so that the self-reflective capacity of waking is partly restored inside sleep.

We can say it has genuine clinical use. Lucid dreaming therapy for recurrent nightmares — including in post-traumatic stress — has trial support, working by allowing the dreamer to recognise the nightmare and alter its course.

We can say the risks are real but modest. Induction techniques that involve deliberately fragmenting sleep reduce sleep quality, which matters if practised heavily. Lucid dreaming is associated with sleep paralysis, which is harmless and extremely frightening. And for people with a history of psychosis or dissociation, deliberately blurring the boundary between waking and dreaming is not obviously advisable. This is not medical advice and anyone with a sleep or psychiatric condition should treat it as a clinical question.

We can say the traditions got there first. Tibetan dream yoga is describing this phenomenon, using it deliberately, with a rationale — that noticing the dream is a dream trains the recognition that waking is similarly constructed. Whether that further claim holds is a separate matter, but the practice they were describing turned out to be exactly real.

We cannot say what lucid dreaming establishes about anything larger. It is a state of the sleeping brain, well characterised. That it was once an unverifiable mystical claim and is now a laboratory technique is the most useful thing about it — and a reasonable answer to anyone who assumes this site's default is scepticism.

Further reading

• LaBerge's original papers, and Exploring the World of Lucid Dreaming (1990).
• Konkoly et al., "Real-time dialogue between experimenters and dreamers during REM sleep" (Current Biology, 2021).
• Keith Hearne's doctoral work (1978), for the first signal.