A lucid dream is a dream in which you know you are dreaming — and, with practice, one you can steer. About half of all people experience it spontaneously at least once, usually in the strange moment of noticing something impossible: text that changes when you re-read it, a mirror that shows the wrong reflection, a room from your childhood attached to your current home. Lucidity can turn a nightmare around, let you practise skills, or simply offer the strangest freedom there is: flying at will.

Step one: a dream journal

Everything starts with remembering. Keep a notebook by the bed and write down whatever you recall the moment you wake, even single images. Within weeks you will notice your personal dream signs — places, people and situations that repeat. Recognising those signs inside a dream is the doorway to lucidity, which is also why studying symbols like stairs, school or the sea in a dream dictionary sharpens your attention to them.

Step two: reality checks

Several times a day, seriously ask: "Am I dreaming right now?" — and test it. Read a line of text twice, look at a clock twice, count your fingers, try pushing a finger through your palm. In dreams these checks fail in telltale ways. Done regularly while awake, the habit carries into dreams, and one night the check will fail — and you will know.

Step three: the MILD technique

Mnemonic Induction of Lucid Dreams, developed by researcher Stephen LaBerge, is the best-studied method. As you fall asleep, repeat a firm intention — "Next time I'm dreaming, I will notice I'm dreaming" — while visualising a recent dream in which you become lucid. It works best combined with waking briefly after five to six hours of sleep and then returning to bed with the intention. Be patient: lucidity is a skill, and like any skill it favours the consistent. Until then, every remembered dream is material — look its symbols up and let the dictionary tell you what your mind keeps returning to.