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At the transition between wakefulness and REM sleep, the dream and waking worlds sometimes collide. Cinematic visions of REM spill over into conscious awakening, like dreaming with your eyes open – sometimes a nightmare on steroids. As if being paralysed when waking weren’t chilling enough, people across the world encounter terrifying bedroom intruders – witches, demons, aliens, vampires and even gigantic cats.

But Harvard neuroscientist Baland Jalal explains these apparitions are a result of the brain’s prediction machine making sense of the impossible, filling in the gaps to construct a new reality – until we awaken and it slowly fades. One of the world’s foremost researchers of sleep paralysis, he sees it as a window onto our brain’s wider functions. Our minds create the dream world and populate it with our own creations – the way we make sense of sleep paralysis and dreams tells us much about our sense of self and of others. Going further, Jalal shows how it is this point on the edge of dreams, stretching the imagination like no other, that enables great artists and thinkers have had their most profound revelations.

Packed with fascinating stories from his research that has taken him all around the world, he explains how our expectations and cultures shape the visions we bring to life. And what this might mean at the deepest level for who we are. Perhaps revealing how the activity of tiny wisps of protoplasm in the brain gives rise to consciousness in all of its complexity, that makes us so uniquely human.

© Baland Jalal 2026 (P) Penguin Audio 2026