Here’s what really happens when people think they’ve seen a ghost

Around a third of us believe in ghosts, and 28% of us have ‘felt the presence’ of a spirit from beyond the grave, according to a 2014 YouGov poll.

For those who have seen or ‘felt’ a ghost, the experiences can be extremely real – but what is actually happening?

It’s all to do with sleep – and ‘exploding head syndrome’ – says Professor Alice Gregory of Goldsmiths.

Gregory writes in an essay for The Conversation that during REM sleep, when we have our most vivid dreams, people are paralysed.

In some people, ‘sleep paralysis’ can continue while they’re awake – leading to dream-like experiences which feel real.

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Gregory says, ‘But during sleep paralysis, features of REM sleep continue into waking life.

‘Those who experience it will feel awake yet might experience dream-like hallucinations and struggle to move.

‘This experience is pretty common, occurring in around eight per cent of people (although estimates vary dramatically depending on who we are asking). ‘

Sleep processes can also explain moments when things go ‘bang’ in the night, Gregory says.

Gregory writes that many such ‘bangs’ can be explained by ‘y ‘exploding head syndrome’, a term coined relatively recently by the neurologist JMS Pearce.

‘When we fall asleep, the reticular formation of the brainstem (a part of our brain involved in consciousness) typically starts to inhibit our ability to move, see and hear things.

‘When we experience a ‘bang’ in our sleep this might be because of a delay in this process. Instead of the reticular formation shutting down the auditory neurons, they might fire at once.’