Experts on sleep psychology at a Lewisham university are researching the mysteries behind “Exploding Head Syndrome”.

Researchers from Goldsmiths, University of London are also researching sleep paralysis and want people to come forward who have experienced unusual sleep symptoms.

Exploding Head Syndrome involves a sensation of an explosion or loud noise when falling asleep or waking up.

It used to be considered extremely rare but is now thought to be fairly common and, despite its name, it is usually painless.

Sleep paralysis involves an inability to move just as a person is falling asleep or waking up. It can be accompanied by unusual perceptions about a person’s surroundings that disappear once they are able to move again.

Alice Gregory, professor of psychology at Goldsmiths and one of the project leaders, said: “While these phenomena can be disturbing recent data suggests that they might actually be fairly common.

“What’s fascinating is that we know so little about why one person may experience them frequently and another never experience them at all.

“There is also a lack of information about how to prevent these experiences from happening.”

Chris French, also a professor of psychology at Goldsmiths, said: “Sleep paralysis is a phenomenon that’s fascinated me for many years. Previous studies report that up to a third of participants say they have had it at one time or another.

“We’re keen to hear from people who have experienced it to tell us what they think might be going on and to help build on our understanding of the condition.”

To take part in the survey, go to sciencefocus.com/bigsleepsurvey