A dream in which you realise you are dreaming while the dream carries on.
The term comes from the Dutch psychiatrist Frederik van Eeden, who used it in the early twentieth century. In a lucid dream the scene is still a dream, but you know it is: sometimes you can only watch, sometimes you can steer what happens. Many people have one at least once, usually by chance and only for a moment, because the thrill of realising tends to wake you. Contemplative traditions treat it as a practice of awareness; science has confirmed it in the sleep laboratory.
How it was proven in the laboratory
For years lucid dreaming seemed impossible to prove: a sleeper cannot announce "I'm lucid now". The answer came between the late 1970s and the 1980s, in England and the United States. During REM sleep, the stage of the most vivid dreams, the body's muscles are still but the eyes are not. So researchers agreed a signal with the dreamers in advance, such as looking left and right several times in a row, to be made as soon as they realised they were dreaming.
The recordings confirmed that those signals arrived while the brain was genuinely in REM sleep. More recent studies have even managed to put simple questions to dreamers and receive answers through the same eye movements. Some research also points to greater activity in the frontal areas of the brain, those linked to reflecting on oneself.
Practices that make it more likely
Tibetan dream yoga has taught people for centuries to recognise a dream as a dream, and treats this as a path of awareness. Modern practices are simpler. The first is remembering your dreams by writing them down as soon as you wake. The second is asking yourself several times a day "am I dreaming?" and genuinely looking around. The third is a clear intention before sleep: next time I dream, I will notice.
Some people also wake in the night and go back to sleep shortly afterwards, because lucid dreams seem to come more often towards morning: if you try it, don't do it every night and don't sacrifice your sleep. SideraMea's dream diary, for subscribers, lets you tag a dream as "Lucid" and read it back alongside that night's sky.
Frequently asked questions
How can you tell if you are dreaming?
In dreams some things don't work properly, and that is where to look. Text changes when you read it twice, a clock shows a different time with each glance, light switches fail, your hands look odd. People who cultivate lucid dreaming run these checks while awake too: the habit carries over into dreams, and sooner or later one of them shows you that you are dreaming.
Is lucid dreaming dangerous?
For most people it is a harmless and often enjoyable experience. The main risk is indirect: chasing it by sleeping less or waking yourself too often. Coming out of a lucid dream, you may occasionally pass through a brief episode of sleep paralysis. If you often find it hard to tell dreams from reality, or these experiences unsettle you, it is better to stop and talk to your doctor.
What is the difference between a lucid dream and an out-of-body experience?
In a lucid dream you know you are dreaming and move through a setting you recognise as dreamt, often unlike your own room. In an out-of-body experience, by contrast, you feel awake and seem to be in the real room, seen from another point. The two do overlap, though: they arise in the same hours of the night, and sometimes one turns into the other.
Keep a dream journal
Writing your dreams down as soon as you wake is the first step to remembering and recognising them. In the SideraMea journal each dream stays next to the sky of that night.