A psychologist explains that those who believe they have had an alien encounter may simply have sleep paralysis or false memories, according to the Daily Mail.
Scientists have a relatively good understanding on why sleep paralysis is caused, Dr French explains.
During deep, or rapid eye movement (REM) sleep, which is associated with dreaming, the body’s muscles are paralysed, perhaps to stop people acting out their dreams.
Sleep paralysis is caused when the mechanisms controlling the sleep cycle are affected so it’s as if the brain is working and the body has yet to catch up.
This means strange imagery, perhaps involving aliens, creeps through into a person’s wakeful consciousness, perhaps inducing terror or a belief in abduction.
However, Dr French notes we should be wary of proposing a ‘one size fits all’ explanation for covering what people think of as alien abductions.
Nigel Watson author of the UFO investigations Manual told, MailOnline: ‘The sleep paralysis theory is good for explaining what are called ‘bedroom invader’ incidents, where people wake in the night to see aliens in their bedroom and experience an abduction.
‘It is harder to explain abductions experienced by people who are driving in their car at night or in other circumstances.’