France-based researcher Dr Isabelle Arnulf discovered in her study that nearly a quarter of her subjects blurted out either something negative or vulgar language as they slept, the website Medical News Today reported.
Of the 232 adults involved in the study, 87 were found to sleep walk or suffer from night terrors. Arnulf also found that 24 percent of the sleep talk contained negative content, while 22 percent turned the air blue with swear words.
The ‘f-word’ accounted for 10 percent of all sleep talk that was recorded – appearing 800 times more frequently during participants’ sleep than their waking hours.
“What we now know is that sleep talking is very similar to talking awake, in terms of correct grammar, with subordinate sentences, and silence for others to answer, as in awake turn of speech,” Arnulf said.
“The differences are qualitative: nocturnal language is negative, tense, more vulgar, and addressed to somebody, not to oneself,” she added.