Many people talk in their sleep at some point in their life—whether they know it or not. In fact, studies suggest 2 in 3 people experience the behavior.
According to Milena Pavlova, MD, a Mass General Brigham neurologist, sleep talking begins inside the brain.
“You’re asleep, but part of your brain hasn’t quite transitioned to sleep mode,” says Dr. Pavlova. “So, you keep doing things in your sleep that normally happen during wakefulness.”
Dr. Pavlova serves as medical director of the Clinical Sleep Laboratory at Brigham and Women’s Faulkner Hospital. She explains why sleep talking occurs, what sleep talking means, and how to manage the nighttime behavior.
Sleep is delicate. When you fall asleep, your brain cycles through 4 different sleep stages. How long the brain stays in one stage, and their order through the night, can determine how refreshed you feel when you wake up and how well you perform during the day.
Disruptions to when, how, or for how long you sleep can alter brain activity at each stage. Abnormal behavior in your sleep, or parasomnias, usually occur from these disruptions.
Pop culture often embellishes these behaviors. A few of the most well-known include:
While some parasomnias, like sleep walking, may put you in danger, sleep talking presents little risk at all—except for the possible embarrassment of a sleep partner overhearing your banter.
The two main triggers of sleep talking in adults are:
Several other factors increase the likelihood of sleep talking. These include:
Sleep talking happens more frequently in children than adults. Half of young children experience the behavior compared to 5% of adults.
Dr. Pavlova believes the development of a child’s brain helps explain why. She lists several possible factors:
The short answer: nothing. The myth of people confessing their deepest, darkest secrets in their sleep occurs only in Hollywood films, not in real-life bedrooms, Dr. Pavlova says.
Most times, sleep talking sounds more like babbling than intelligible sentences.
“If you’re looking for an elixir of truth, sleep talking isn’t it,” she adds. “That’s a myth that’s persisted for decades.”
Sleep talking, while largely harmless, sometimes signals a more serious condition in adults.
The stages of sleep are characterized as either rapid eye movement (REM) or non-rapid eye movement (non-REM). During REM sleep, the brain paralyzes the entire body, except for those muscles controlling the eyes and organs essential for breathing. Dreaming occurs during this type of sleep, too.
When someone acts out purposeful movements, such as talking or walking, during REM sleep, the part of their brain responsible for restraining muscle movement has malfunctioned. This condition, called a REM behavior disorder (RBD), allows people to act out dreams. These individuals put themselves, or others, in danger, especially if they act out violent behaviors.
“RBD can start with benign talking but transition into shouting and gradually turn into violent actions,” says Dr. Pavlova. “They might try kicking or punching air. Some may fall right out of bed.”
Only 1% of people develop RBD. However, those who do often develop Parkinson’s disease, leading many to wonder whether a link exists between the two.
RBD is associated with:
People often talk in their sleep without realizing it. Sometimes, only a sleep partner makes them aware of the behavior.
Those same sleep partners can help recognize the early signs of RBD. People with RBD often wake up remembering elaborate dreams. Their sleep partners may recall whether they spoke out specific parts of that dream in their sleep.
Only a doctor can diagnose RBD using a sleep study. The study determines which stage of sleep their talking occurs. Individuals must undergo testing in a laboratory, as opposed to an at-home sleep test, to measure brain wave activity from electroencephalogram (EEG).