Have you ever wondered why don't we sneeze during sleep? Try to remember if you've ever woken up from a loud sneeze in the middle of the night? Most likely, no. Many scientists working in the field of sleep studies believe that sneezing during a night's rest is almost impossible. Although there have been no serious scientific studies on this topic, physiologists and neurobiologists have been able to explain this phenomenon based on how our brain and body work when we sleep. Let's try to figure out why this happens.
Maybe we do sneeze in our sleep and just don't remember it? Image source: Times Union
Contents
- 1 Why a person can't sneeze in their sleep
- 1.1 There are fewer irritants at night
- 1.2 Sleep prevents us from sneezing
- 2 What happens during slow-wave sleep
- 3 What happens during rapid-wave sleep
Why a person can't sneeze in their sleep
According to Popular Science, when we sleep, our bodies work very differently than when we are awake. Sneezing is a reflex that usually occurs in response to irritants, such as dust or allergens. However, when we sleep, the response to these irritants seems to not occur. Sleep researcher Steven Shea noted that he has observed hundreds of people sleeping and has never seen them sneeze.
People can snore in their sleep, but they can’t sneeze. Image source: mir24.tv
He had never even seen anyone cough in their sleep. He once worked with a boy who, due to a chronic illness, coughed every 10-15 seconds during the day. But as soon as the boy fell asleep, the cough disappeared. It was as if his brain “switched off” this reflex during sleep. Every time the boy woke up, the cough returned, but disappeared again when he fell asleep again.
This story suggests that our brains “mute” reflexes during sleep, including sneezing and coughing, allowing us to rest peacefully. Most likely, we do not sneeze or cough during sleep for several reasons.
Read also: What happens in our body when we sneeze – it is a complex and important process
There are fewer irritants at night
One of the main reasons why we do not sneeze in our sleep is that there are fewer irritants around us at nightWhen we sleep, there are no people or pets nearby to stir up dust.
Nothing happens at night, so there are a minimum of irritants. Image source: Mix News
The photic reflex also doesn't work at night— a phenomenon when we want to sneeze from bright light — the darkness in the room will not allow this to work. All these factors reduce the likelihood that something will cause a sneeze during a night's rest.
Sleep prevents us from sneezing
A deeper reason why we do not sneeze in our sleep is that some of our reflexes are blocked.
During the night, we are in two sleep modes, REM and NREM. Rapid eye movement sleep, during which our eyes move chaotically under our eyelids, takes up about 25% of our time, and it is during this period that we experience our most vivid dreams. The rest of the time is taken up by slow-wave sleep, during which we truly rest and many processes within our body are in a full-fledged sleep mode.
During REM sleep, our eyes move around under our eyelids. Image source: The Filipino Times
These two conditions have different effects on why we don't sneeze during sleep.
What Happens During NREM Sleep
In slow sleep, especially in its deep phase, our brain actively filters external stimuli. For example, a light touch to the hand during slow sleep does not cause such a strong reaction in the brain as in the waking state. This has been proven in scientific experiments: the brain of a sleeping person shows much less activity than that of a waking person with the same stimulation. This is why sometimes you have to shake a person hard to wake him up.
During deep sleep, the thalamus and the cerebral cortex, which are responsible for processing sensory signals, work together to suppress external stimuli. This process does not completely block all signals, but it significantly hinders their penetration into the brain.
During sleep, the human brain actively blocks signals about irritants. Image source: stock.adobe.com
However, if the irritant is strong enough — for example, if a person smells smoke or has an attack of apnea — the brain immediately reacts and wakes us up. The same thing would happen if something really strong made us sneeze. We would wake up and only then sneeze.
You might be interested in: Why people can’t hear themselves snore
What happens during REM sleep
During REM sleep, a different mechanism is at work. During this state, our brain “turns off” our body so that we don't start moving in response to what's happening in our dreams. Sneezing is a complex, coordinated muscle action, but during REM sleep, many of our muscles are virtually paralyzed. So even if something could trigger a sneeze, it's nearly impossible to do so in a dream because muscle movement is blocked.
The body's “switching off” causes a frightening phenomenon called sleep paralysis. Image source: Man Today
The bottom line is that we can't sneeze during sleep for three reasons. First, at night, our sensory organs are rarely irritated. Second, in deep sleep, we react less to irritants because the brain blocks them. Third, in REM many of our muscles are paralyzed. If we sneeze in our sleep, it happens during short periods of awakening.
A person can sneeze only if they suddenly wake up. Image source: Health Day
It is important to note that some scientists still believe that we sneeze during sleep. For example, researcher Matt James is sure that at night we sneeze, we just don't notice it or forget. But it's hard to believe – have you ever seen a person sneezing while fast asleep? Hardly.
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Finally, it is worth noting that if you want to sneeze, you cannot hold back. This can be deadly.