Sleep Talking
Category: Sleep Science
Neurological Mechanisms of Sleep Talking
During ordinary sleep, the brain keeps up 'muscle atonia' (the suppression of voluntary muscle activity). During REM sleep in particular, inhibitory mechanisms in the brainstem cut off motor commands to the skeletal muscles, so the body stays still no matter how much you run or shout inside a dream. Sleep talking happens when that inhibition works only incompletely on the muscles involved in speech.
The motor system for speech is controlled partly independently of the other skeletal muscle systems, and it isn't always fully subject to REM atonia. Sleep talking in NREM sleep clusters around the shift from deep sleep to light sleep, when part of the brain becomes active while muscle relaxation is still incomplete. In polysomnography, a micro-arousal often appears in the EEG just before someone talks in their sleep.
Relationship Between Sleep Talking and Dream Content
One view holds that sleep talking during REM sleep corresponds closely to dream content. Words spoken in REM sleep frequently overlap with the dream the sleeper describes when woken immediately afterward. Sleep talking comes out especially readily in the middle of a dream of conversing with someone.
What makes this interesting is that the linguistic character of sleep talk differs from waking speech. Negative emotional expressions such as 'no' and 'stop,' along with imperatives, are common, while polite forms and social phrasing thin out. Speech inhibition seems to loosen most easily while an emotionally charged scene is unfolding in the dream. Sleep talk also often contains grammatically well-formed sentences, which suggests that the basic machinery of language processing keeps working through sleep.
Frequency and Triggering Factors
About 5% of adults talk in their sleep habitually, and more than 60% do so at least once in their lifetime. Frequency peaks in childhood, between the ages of 3 and 10, and falls off with growth, though it persists in a certain proportion of adults. Constitution appears to play a part as well: identical twins are known to match each other more closely than fraternal twins in whether they talk in their sleep.
Triggers include psychological stress, accumulated sleep debt, alcohol, fever, and a change of sleep environment such as a hotel room on a trip. Sleep talking also coexists frequently with other parasomnias such as sleepwalking and night terrors, which may point to a shared neurological substrate. In REM sleep behavior disorder (RBD) it increases markedly, and in that case it deserves attention as a possible prodromal sign of neurodegenerative disease.
Sleep Talking from a Dream Interpretation Perspective
Seen from the standpoint of dream interpretation, sleep talk can serve as a valuable 'window' into the content of a dream. What a partner or a family member writes down fills in fragments the dreamer could no longer reach after waking. Words that escape during a dream of strong feeling may carry what the unconscious most wanted to say.
Interpretation still calls for care. Sleep talk mirrors only a part of the dream, and a fragmentary utterance cut loose from its context invites misreading. Sleep talking in NREM sleep corresponds only loosely to dream content and sometimes amounts to nothing more than a neurological event. When you put sleep talk to use in dream analysis, the important thing is to set it beside the dream you remember after waking and read it within the whole context.
Was this article helpful?