Sleep glossary
Sleep talking
Why people talk in their sleep, which stages it happens in, whether it means anything, and what a recording can and cannot tell you about it.
In short
Sleep talking is speech during sleep, usually brief and often unintelligible. It is common, it can happen in any stage, and there is no good evidence that what is said reveals anything meaningful about the sleeper.
Sleep talking is also called somniloquy or talking in your sleep.
Sleep talking, or somniloquy if you want the clinical term, is speech produced during sleep. It is common, more so in children than adults, and it can occur in both REM and non-REM stages. Episodes are usually short, often a few words, and frequently not intelligible at all. The popular idea that it reveals something the sleeper is concealing has nothing much behind it.
It matters here for a duller reason: it is one of the things a phone on a nightstand can actually detect. Tock uses Apple SoundAnalysis to classify sounds on the device itself, and sleep talking is one of the categories alongside snoring and coughing. The clip is saved and pinned to the minute it happened, so in the morning you can play back what the room did rather than trying to reconstruct it.
What a recording can and cannot establish
It can tell you that something happened and when. That is genuinely useful, because a night’s sounds are otherwise entirely unavailable to the person who made them, and because a partner’s report is a summary rather than a record.
It cannot tell you why, and it cannot tell you whose sound it was. A phone has no way to separate two sleepers in one room, which is a real limitation on any night-time audio feature and one worth knowing before drawing conclusions from it. What your phone can actually hear at night goes through the mechanism and its edges.
Where sleep talking arrives suddenly in adulthood, or comes with more physical night-time behaviour, that is a pattern for a doctor rather than an app. Tock records and classifies sounds and does not diagnose anything.
Questions people ask
Does sleep talking mean anything?
There is no good evidence that the content reveals anything about what somebody is thinking or hiding. It is usually fragmentary and frequently unintelligible, and treating it as a window into someone is not supported by anything.
Should I be worried about sleep talking?
On its own, generally not. It is common and mostly harmless. It is worth mentioning to a doctor when it starts suddenly in adulthood, or arrives alongside acting out dreams or other unusual night-time behaviour, which are different things.