Nasal congestion during sleep, but it gets better after waking up, generally consider the following situations: 1. The possibility of allergic rhinitis, when people sleep, the parasympathetic nerve is relatively excited, resulting in enhanced nasal gland secretion, which can lead to nasal obstruction symptoms, after waking up, the sympathetic nerve is relatively dominant, so nasal gland secretion is reduced and the nasal cavity becomes clear. 2. The allergic rhinitis can be triggered by the stimulation of allergens, causing congestion and edema of the nasal mucosa and nasal congestion. 3. structural abnormalities of the nasopharynx, some patients have a thick soft palate or a loose tongue root muscle, which can easily block the nasopharyngeal passage when sleeping flat, resulting in a feeling of nasal congestion.