The sight of a baby sleeping with their mouth slightly open is common, often sparking questions about whether it is normal or a sign of an underlying issue. Newborns naturally breathe almost exclusively through the nose; mouth breathing usually occurs temporarily due to a blocked nasal passage. Occasional open-mouth sleeping is generally not concerning, but when it becomes a consistent habit, it signals a need for closer attention. The distinction between temporary and chronic mouth breathing determines if intervention is necessary.
Primary Causes of Open-Mouth Sleeping
Open-mouth sleeping is frequently a direct response to a temporary obstruction in the nasal passages, forcing the baby to seek an alternate route for air intake. The most common temporary cause is nasal congestion due to a cold, flu, or mild allergies. When mucus blocks the small, narrow nasal passages, infants instinctively open their mouth to breathe more easily.
The baby’s sleeping position can also influence whether their mouth falls open during deep rest. When muscles relax significantly during sleep, the jaw may drop, especially if the head position encourages it. Anatomical factors, such as a tongue-tie, can prevent the tongue from resting properly against the roof of the mouth and contribute to oral respiration.
As babies mature, their ability to reflexively breathe through their mouth when the nose is blocked develops, typically around three to four months of age. If mouth breathing persists after a congestion-causing illness has cleared, it can sometimes turn into a learned habit. The body adapts to the easier mouth-breathing pattern, even when the nasal airway is clear.
Potential Health and Developmental Concerns
While temporary mouth breathing is harmless, chronic open-mouth sleeping can affect a child’s health and development over time. One immediate effect is oral dryness, which diminishes the protective role of saliva. Saliva neutralizes acids and washes away bacteria, so a consistently dry mouth increases the risk of dental issues like gingivitis and tooth decay.
Prolonged mouth breathing can interfere with the proper development of the jaw and face, as significant craniofacial growth occurs early in life. When the mouth is habitually open, the tongue rests low instead of against the palate, which supports proper bone growth. This can contribute to a narrower jaw, a high-arched palate, and malocclusion (misaligned teeth), potentially necessitating orthodontic treatment later.
The quality of rest is also affected, as mouth breathing is less efficient than nasal breathing, which naturally filters, warms, and humidifies the air. Chronic oral respiration can be a sign of sleep-disordered breathing, leading to poorer sleep quality and daytime fatigue. This can manifest as difficulty focusing, irritability, or behavior changes during the day.
When to Consult a Pediatrician
It is important to seek professional guidance when open-mouth sleeping is a consistent pattern. Parents should consult a pediatrician if they observe loud snoring or noisy breathing during sleep, as this can signal a partial airway obstruction, potentially from enlarged tonsils or adenoids. Enlarged adenoids are more common in children two to four years old, but they can affect younger infants as well.
A medical evaluation is warranted if the baby exhibits signs of sleep apnea.
Concerning Signs
- Gasping, choking, or noticeable pauses in breathing during sleep.
- Visible effort or retraction, where the skin pulls in around the chest, ribs, or neck, while the baby is breathing.
- Chronic, persistent nasal congestion not relieved by home remedies or associated with a cold.
- Persistent irritability or poor weight gain.
Strategies for Encouraging Nasal Breathing
Parents can implement strategies to support clear nasal passages and encourage nasal breathing. Keeping the nasal airway clear is the primary goal, especially since newborns are preferred nasal breathers. Saline nasal drops can be used to thin mucus, followed by gentle suction with a bulb syringe or nasal aspirator to remove the congestion.
Running a cool-mist humidifier in the baby’s room can help by adding moisture to the air, which prevents nasal dryness and helps to loosen thick mucus. Ensuring the baby is adequately hydrated also helps to keep secretions thin and manageable.
For a baby with congestion, safely elevating the head of the mattress slightly, by placing a firm object under the mattress, can assist with mucus drainage. Note that no pillows or loose bedding should ever be placed inside the crib.
For babies whose mouth breathing has become a habit, gently encouraging a closed-lip posture when they are awake can reinforce nasal breathing. This action promotes the correct resting position for the tongue, which is foundational for optimal facial and airway development. Introducing textured foods and chew toys at the appropriate stage can also strengthen oral muscles and support the growth of a wide, healthy jaw.