Scientists studied what sleep talkers said in their sleep — and found out who curses most

Sheet happens during pillow talk.

There’s a slew of bizarre behaviors during sleep, and while sleep talking may be the least unusual, it’s possibly one of the most common, with studies suggesting around 2 in 3 people exhibit the behavior.

Researchers decided to take a closer look at what sleep talkers are yapping about, including the most common words, topics and who’s swearing up a storm.

While little is known about the mechanisms behind sleep itself, research suggests that sleep talking happens during rapid eye movement Sleep Behavior Disorder (RBD), where the region of the brain that paralyzes speech and movements during sleep fails to function effectively.

Also known as somniloquy, sleep terrors, stress, medications and more can also cause sleep talking, affecting men and women equally.

However, a study published in the journal Sleep found that sleep talk is full of negative and vulgar words often directed towards another person, with nearly 10% of clauses containing profanity, with F-bombs appearing around 800 times more during slumber.

And not only were men more verbal in this particular study, but they also cursed more.

Of 232 participants, 129 had RBD; 87 experienced sleepwalking, sleep terrors or both; one person had sleep apnea and 15 adults had no sleep-related disorders.

Researchers used video polysomnography to record any speech episodes as participants slept over the course of two nights.

Frequency of speech episodes, words each person said, whether they spoke positively or negatively and whether or not their words were aimed at others were all monitored and recorded.

Of the 883 speech episodes, or periods where they talked, the participants said 3,349 understandable words, excluding mumbles, shouts or whispers.

The most common word uttered? No, with negations representing 21.4% of clauses and more observed during non-rapid eye movement (REM) sleep.

Swearing was predominant in non-REM sleep, whereas verbal abuse lasted longer during REM sleep and was mostly directed toward insulting or condemning someone.

The biggest takeaway from the study was that sleep talking was very similar to awake talking in terms of grammar, semantics and pauses in conversation when waiting for another person to respond.

Language used during sleep often mirrored that of a familiar, yet tense conversation that respected language gaps or pauses to let someone else talk.

However, we’re much more vulgar, negative and tense when talking to someone else, rather than just ourselves while we’re asleep.

Researchers believe this means the sleeping brain can function at a high level, comparable to when we’re awake.

Sleep talking is just one example of parasomnias, unusual movements and behaviors that occur while falling asleep.

Previous research found that women are twice as likely to handle electricity or kitchen tools or perform similarly complex activities compared to men while sleepwalking.

And younger adults and children are more likely to sleepwalk compared to older people, according to a 2024 study published in the Journal of Clinical Neuroscience.