You might think sleep is a time of peaceful rest, but a new study suggests visiting the Land of Nod can make us quite angry.
Researchers in France listened to 232 people as they slept over two nights, recording what they said - and it wasn't pretty.
The most common word they heard was 'no', and almost 10 percent of sentences contained a profanity. F**k was spoken about 800 times more frequently than normal.
During REM sleep - dreaming - verbal abuse was common, "mostly directed toward insulting or condemning someone".
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Around a quarter of the time, the person sleeping was either being interrogated or delivering an interrogation when they spoke.
Men talked more in their sleep than women, and were more likely to swear too.
Around 59 percent of everything the volunteers said was non-verbal.
Surprisingly, despite the reputation sleeptalking has for producing nonsense phrases, the study found the majority of the intelligible speech recorded followed grammatical rules.
"Sleeptalking is very similar to talking awake, in terms of correct grammar, with subordinate sentences, and silence for other[s] to answer, as in awake turn of speech," lead researcher Dr Isabelle Arnulf told Medical News Today.
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It's still not known what causes sleeptalking, but research suggests it's when the part of the brain that's meant to paralyse movement during sleep fails to function properly.
The findings were published in journal Sleep.