Why Do People Sometimes Talk While Sleeping?

Sleep is a great thing, particularly because it’s the best form of rest that anyone can get. A good night’s slumber is all you need after a tiring day at work. However, does everyone experience sleep in the same way?


Credits: Andrey_Kuzmin/Shutterstock

You must have heard (or heard about) people speaking in their sleep. However, you probably wouldn’t be able to make any sense out of whatever the person was saying, because most of the times the words and sentences are entirely incoherent. Still, there are instances where people actually speak entire sentences that can be understood! In that case, how is it possible that people speak while their mind is, supposedly, on ‘rest’ mode?

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The Name is Somniloquy

The condition, which we talked about, is called somniloquy, more commonly known as sleep-talking. Speech while sleeping can be very soft or inaudible (like a mumbling noise) or it can be very loud, which, at times, can even escalate to shouting or howling. This is a common condition that many people experience while sleeping.

Release of Paralysers by the Brain

When you fall asleep, the reins of the overall functioning of your body are handed over to the Ventrolateral Preoptic Nucleus (VLPO) from the Reticular Activating System (RAS). However, precisely when does this transition take place?

You must have felt your body twitching during sleep. Well, that’s the time when this transition occurs. Once the brain has entered the mode of complete sleep, it undergoes four stages, including the stage of Rapid Eye Movement (the stage of dreams).


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When your body is asleep and at rest, your brain releases two chemicals, glycine and GABA (gamma-aminobutyric acid). These chemicals paralyze some of your organs, including your vocal chords, body muscles, mouth, and others. This is the reason that no matter how hard you try to move your legs, you are not able to force them into action to flee from a bunch of vampires chasing you through your dream, or why you are not able to utter your own name properly, no matter how you try to twist and warp your mouth.

Why Do People Speak While Sleeping?

Now we know that most of us can only manage to speak gibberish during sleep, but that brings us to the next question. Why do some people speak so loud and clear and in such meaningful sentences?

Scientists are not clear about the exact reason why people are able to break into a monologue in the midst of their slumber, but they have a few possible explanations. Since sleep-talking is most likely to occur when a person is dreaming, one viable hypothesis is that people may sometimes escape the ‘enchantment’ of glycine and GABA released by their own brain and end up speaking whatever it is that they are witnessing in their dream. This is also known as ‘motor-breakthrough’, the state when a person ‘breaks through’ the chemical-induced paralysis typically provided by the brain.

Another hypothesis is that sleep-talking may be related to ‘transitory arousal’. This happens when a person is switching between different sleep stages, which is more commonly associated with sleep-walking and night terrors (when people scream or shout in fear).

Is It A Bad Thing?

Not particularly, unless you are waking up the other person sleeping in your room at regular intervals. Almost all children, and many adults, talk in their sleep. A random ‘hey there’ and ‘say what’ occasionally spoken during sleep is nothing to worry about, but if sleep-talking persists even after the age of 25, it is strongly recommended to get professional advice about the issue.

We don’t want to say that sleep-talking makes a person crazy or anything, it is just a way to make sure that everyone is same when they get behind the wheel of a car!

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About the Author

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spearheads the content and editorial wing of ScienceABC and manages its official Youtube channel. He’s a Harry Potter fan and tries, in vain, to use spells and charms (Accio! [insert object name]) in real life to get things done. He totally gets why JRR Tolkien would create, from scratch, a language spoken by elves, and tries to bring the same passion in everything he does. A big admirer of Richard Feynman and Nikola Tesla, he obsesses over how thoroughly science dictates every aspect of life… in this universe, at least.

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