Wake up at the back!

ARE you asleep? If the answer seems obvious, think again. We are starting to learn that there is a strange twilight zone between sleep and wakefulness (see “The twilight zone”). Some of the resulting altered states are rare, which is fortunate when it comes to somnambulant attempts at violence. Others, such as sleep paralysis, are harmless, if sometimes alarming. All could be caused by parts of the brain going “offline”, unbeknown to its owner. So, unexpected as it may seem, valid answers to the above question include yes, no – and maybe.