If your baby’s nose is normal during the day but not at night, consider that it may be related to allergic rhinitis, adenoid hypertrophy and other factors. 1. Allergic rhinitis: When babies sleep at night, they may come into contact with allergy-inducing substances such as dust mites on the quilt sheets. These allergic substances can lead to the onset of allergic rhinitis and induce the body to produce an allergic reaction, resulting in the situation of the nose not being able to breathe at night. 2. Adenoid hypertrophy: The baby’s own adenoid hypertrophy may lead to poor ventilation of the nasal cavity during sleep. There may be other clinical reasons why a baby’s nose is normal during the day but not at night. Parents should bring their babies to the ear, nose and throat department of the hospital as soon as possible to receive treatment under the guidance of professional doctors.