If you’re prone to nightmares, then you know what it’s like to try to scream in your sleep: No matter how bad your brain’s conjurings are, it’s as if your jaw has been wired shut. It’s undoubtedly a terrible feeling, but the question remains: Why does it happen?
As unnerving as this experience may be, experts say that this is actually your body’s way of preventing you from acting out your dreams.
“Typically we have the urge to scream or shout when we’re going through a bad dream or a nightmare. Scream[ing], in this case, represents our built-up anger or fear. The inability to scream, as well as run or punch someone in your dream, appears because your brain areas that control motor neurons are switched off during sleep,” explains Julie Lambert, a certified sleep expert from Happy Sleepy Head. “Motor neurons are responsible for any muscle contractions. Since your pharynx and tongue, which are used to make a scream, are muscles too, you cannot scream when asleep.”
For those who suffer from sleep paralysis – a fairly common condition during which a person continues to be unable to move or speak for a brief period of time upon waking up—the inability to scream may can even continue into consciousness.
“You experience dreams in the REM sleep phase, and the activity in certain parts of your brain during this phase is very similar to that of the waking state,” Lambert says. “If your dreams are very vivid or feel real, you may even wake up from them. But waking up the motor neurons in your hands and legs takes time, which often results in the feeling of paralysis. Thus, you may feel like you’re going to scream, but can’t.”
If you’re reading this article and thinking to yourself, “This can’t be true! I scream in my sleep every night!” then you are the rare exception to the rule. Those who suffer from a condition known as sleep or night terrors are able to act out their dreams, and folks with this terrifying condition often end up sleepwalking, screaming, or even hitting someone while still asleep.
“Sleep terrors are uncommon in adult people, but some individuals, such as those who abuse alcohol and drugs, may experience them. Unlike sleep paralysis, sleep terrors appear during the transition from stage 3 to stage 4 of non-REM sleep, when your muscles aren’t completely relaxed. In this case, you may scream or run from danger just like you would do in the state of wakefulness,” explains Lambert.
If you’re a rather loquacious sleeper, then you’re probably wondering how it’s possible that you can talk in your sleep but can’t scream. Well, the reason for this distinction is that the two activities take place during difference sleep stages. In other words, sleep-talking does not generally happen when you are in the REM sleep cycle—the same cycle during which nightmares tend to take place.
“Our mind and bodies have this built-in function essentially to prevent us from moving around in a deep sleep,” Bill Fish, a certified sleep coach and co-founder of the sleep wellness website Tuck Sleep, explains. “Many of us to talk in our sleep or even kick or move our arms, but this would be when we are not currently in a deep sleep cycle.”
So how can you avoid the nightmares that make you want to scream in the first place? Aside from seeking help from a sleep consultant, the best way to prevent these bad dreams and all of the emotional turmoil they cause is by practicing good sleeping habits.
“To combat nightmares, it is recommended to do everything you can to decompress before bed,” Fish says. “Charge your electronics in another room, read a book, listen to a light podcast, or even meditate. That way your brain isn’t filled with negative clutter as you fall to sleep. If you are still experiencing more than one nightmare per week, it is recommended that you see a sleep specialist for further monitoring.”