Sleep talking, also known as somniloquy, can include:
- talking in whispers
- speaking at a regular volume
- shouting single words or responses
- saying full, intelligible sentences or holding entire conversations
- producing garbled, nonsensical speech mixed with grunts and other noises
No matter which version occurs, chances are you won’t know you’re talking in your sleep unless you wake yourself up while speaking or someone else tells you about it later.
Deirdre Barrett, a psychologist and long-time dream researcher at Harvard Medical School, says that sleep talkers might describe an important or memorable thing from their lives once in a while, but it’s often mixed in with gibberish that makes it difficult to tell fantasy from reality.
“The idea that a sleep talker is always going to be telling the truth about waking reality is definitely not the case,” says Barrett. Instead, she emphasizes that sleep talking is nothing to worry about, even if the messages seem anxious or frightened, which, according to the psychologist, is common and normal.
Research suggests that up to 20 percent of children and six percent of adults are frequent sleep talkers.
Sleep talking can occur during any stage of sleep, whether it’s rapid eye movement (REM) sleep or not. Since most body movements—aside from eye movements—are temporarily paralyzed during REM sleep, Barrett says that any sleep talking that emerges during this stage is related to a failure in the neural signals inhibiting movement.
However, sleep talking happens much more frequently during non-REM sleep. Because non-REM sleep doesn’t involve paralysis, Barrett says that sleep talking during this stage is thought to be caused by "partial awakenings" of brain regions involved in language production. These brief activations can be detected using electrodes placed on the scalp, known as EEG.
"The person wouldn't show a full waking EEG, but they'd show little areas of the brain or moments [in time] that look somewhat awake rather than like normal non-REM sleep," she says.
That means anything that’s known to disrupt your sleep could contribute to sleep talking, including:
- jet lag
- sleep deprivation
- sleep apnea
- anxiety and stress
- alcohol or substance misuse
“In REM, you just hear anything you can imagine,” says Barrett. She’s often heard recordings of sleep talkers going on monologues, or appearing to have a conversation with someone (and waiting the appropriate amount of time for the other person to answer). More rarely, people will even sleep talk both sides of a conversation. “They tell jokes, they laugh, they cry, they sing songs — just about any kind of verbalization that you could do awake, they do,” Barrett says, but adds that generally the speech is not as logical as what someone would say while awake.
