in children is not a good symptoms and you need to ensure that enlarged adenoids
and tonsils are not the cause for this.
Enlarged adenoids (that are lymph
nodes at the back of the throat, above the tonsils) and tonsils put pressure on the upper airway, which is why children either need to mouth breathe or the air that cannot pass causes the snoring sound.
Sometimes, secretions from these enlarged glands can pool at the back of the throat and come out of the mouth.
Most children are unable to get a good night's sleep due to all this, and wake up irritable, fatigued due to unrefreshing sleep.
I hope this helps.