We don't sneeze while sleeping because the nerves responsible for triggering a sneeze are inactive during sleep. This is especially true during REM (Rapid Eye Movement) sleep.
The Science Behind It
Sneezing is a complex reflex involving sensory input, nerve signals to the brain, and muscle activation. During sleep, particularly deep sleep (REM), these processes are suppressed.
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Nerve Inactivity: The nerves that initiate the sneeze reflex are essentially at rest during sleep. These nerves are responsible for detecting irritants in the nasal passages and sending the signal to the brain to trigger the sneeze. [Source: Multiple articles cited below confirm this.]
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REM Sleep and Muscle Paralysis: During REM sleep, the body experiences atonia, a temporary paralysis of voluntary muscles. This prevents us from acting out our dreams but also inhibits the muscular contractions required for sneezing. [Source: Numerous sources from Healthline, Medical News Today, Sleep Foundation, GoodRx, Amerisleep, and Reddit confirm the connection between REM sleep and muscle inhibition. ]
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Non-REM Sleep: While the information about sneezing during Non-REM (NREM) sleep is less conclusive, it is generally accepted that the likelihood of sneezing is significantly reduced due to a similar dampening of nerve activity and muscle responsiveness. [Source: Sleep Foundation states that the possibility of sneezing in NREM is unclear, implying a low probability.]
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Sensory Input Reduction: Our sensory perception is significantly dulled during sleep. This means that even if an irritant were present in the nasal passages, the brain might not register it strongly enough to trigger the sneeze reflex. [Source: The Guardian notes that voluntary muscles are generally switched off during sleep, reducing the likelihood of involuntary reflexes like sneezing.]
In Summary
The inability to sneeze during sleep is a protective mechanism. The suppression of the sneeze reflex and voluntary muscle activity during sleep safeguards against potential disruptions to rest and ensures that our sleep is not disturbed by this reflex. While it is not completely impossible to sneeze during very light sleep, it is highly unlikely.
