Asked by: James Slatter, by email
A lucid dream is when you know, at the time, that you’re dreaming. The sensation is like ‘waking up’ in your sleep. You seem more alert, logical and self-aware and can even take control of the dream. Some lucid dreamers choose to fly, others seek out a sexy dream partner and a rare few use the opportunity to meditate.
I don’t know why lucid dreaming should seem impossible but it is becoming clearer how it works. Experiments, though difficult, can be done with expert lucid dreamers who can signal to an experimenter using eye movements. Their lucid dreams most often occur towards morning, at the end of a period of REM sleep and when the brain is more than usually active.
Recent brain scans show the most active areas to include parts of the prefrontal cortex and the temporoparietal junction where internal and sensory information come together to form our body schema and self image. This is probably why I feel more awake and ‘myself’ when I realise I’m dreaming.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.