It is harmful to cover our face while sleeping because , when we cover our face we are not able to take fresh Oxygen , we take in CO₂ and release CO₂  . Due to which the CO₂ level in our body or blood increases and we feel suffocation. 
It may lead to dead  or many other problems .
So , we should never sleep by covering our face.
The Brainliest Answer!
We take our co2 when we close our it is harmful to close our face while we sleep.
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