Many patients with rhinitis have this problem: the symptoms can be controlled during the day, but at night, symptoms such as nasal congestion, runny nose, and sneezing suddenly worsen, and even affect the quality of sleep. This phenomenon of "lighter during the day and heavier at night" not only makes people toss and turn, but also may cause problems such as mental fatigue and decreased attention the next day. It is not accidental that rhinitis gets worse at night, but is the result of the combined action of multiple physiological and environmental factors.
Posture change: nasal "congestion" under gravity
When the human body lies flat, the physiological state of the nasal mucosa will change significantly, which is the direct cause of worsening nasal congestion at night.
- Increased blood return: When lying flat, the head is at the same level as the heart, and the venous return resistance of the nasal mucosa is reduced, resulting in blood congestion in the nasal cavity and increased swelling of the mucosa. This swelling will directly compress the nasal concha, narrow the nasal passage, and cause nasal congestion.
- Retention of secretions: When standing or sitting during the day, nasal secretions naturally flow downward due to gravity and can be discharged by coughing or swallowing; when lying flat, secretions tend to accumulate in the back of the nasal cavity, forming "nasal reflux", irritating the throat and causing coughing, further aggravating discomfort.
- Influence of nasal cycle: The human nasal cavity has a natural "nasal cycle" (alternating congestion for about 2-7 hours). Staying in the same sleeping position for a long time at night may prolong the congestion time of one side of the nasal cavity, resulting in aggravation of unilateral or bilateral nasal congestion.
Allergen exposure: "invisible trigger point" in the bedroom
Nighttime is the peak period for many allergens to be active. Dust mites, animal dander, mold and other tiny particles in the bedroom environment may become the "trigger" of rhinitis.
- Dust mite breeding: Mattresses, pillows, and bedding are the main habitats of dust mites. According to the American Academy of Allergy and Immunology (AAAAI), a mattress used for one year may contain 2 million dust mites. At night, the body dissipates more heat, the temperature of bedding rises, and the activity of dust mites intensifies. Their excrement and body fragments enter the nasal cavity with breathing, inducing allergic reactions.
- Pet companionship: If pets are allowed to enter the bedroom, the allergens in their dander, saliva and urine will adhere to the bedding and carpets. The contact time between people and pets at night is prolonged, and the exposure to allergens increases, resulting in aggravated symptoms such as nasal itching and sneezing.
- Mold reproduction: Mold spores in humid areas such as bathrooms and kitchens may enter the bedroom through air circulation, especially at night when ventilation is poor, the mold concentration increases, irritating the nasal mucosa and causing inflammation.
Hormone level fluctuations: "night game" between melatonin and cortisol
Human hormone levels change with circadian rhythms, and hormone fluctuations at night may indirectly affect the sensitivity of the nasal mucosa.
- Increased melatonin secretion: Melatonin is an important hormone for regulating sleep, and its secretion peaks at night. Studies have shown that melatonin may aggravate inflammatory symptoms by enhancing the activity of the immune system and making the nasal mucosa more sensitive to allergens.
- Decreased cortisol levels: Cortisol has anti-inflammatory effects, and its secretion is circadian, with the highest level in the early morning and the lowest level at night. When cortisol levels decrease at night, the anti-inflammatory ability of the nasal mucosa is weakened, and even contact with a small amount of allergens may trigger a stronger allergic reaction.
- Parasympathetic nerve excitement: Parasympathetic nerve activity is enhanced at night, resulting in vasodilation of the nasal mucosa and increased glandular secretion, further aggravating nasal congestion and runny nose.
Environmental factors: "Night traps" of dryness, pollution and temperature
Slight changes in the bedroom environment may become an "accomplice" in the aggravation of rhinitis.
- Dry air: When using heating in winter or air conditioning in summer, indoor humidity may drop below 30%. Dry air deprives the nasal mucosa of moisture, causing the mucosa to dry and crack, reducing the defense against allergens and pathogens, and causing or aggravating inflammation.
- Air pollution: If the bedroom is close to the road or factory, there will be fewer vehicles and lower wind speed at night, and pollutants (such as PM2.5 and nitrogen dioxide) will easily accumulate near the ground, enter the nasal cavity through breathing, and stimulate the mucosa to cause symptoms.
- Temperature changes: The temperature drops at night, and the cold air directly stimulates the nasal mucosa, which may cause vasoconstriction and spasm, leading to worsening nasal congestion; if you are suddenly exposed to cold air from a warm bed, the temperature difference stimulation may also induce sneezing and runny nose.
Gastroesophageal reflux: Stimulation of "invisible reflux" at night
Gastroesophageal reflux disease (GERD) is more common at night, and reflux (gastric acid, pepsin) may enter the nasal cavity through the throat, irritating the nasal mucosa and causing inflammation.
- Lying flat aggravates reflux: When lying flat at night, the pressure of the lower esophageal sphincter decreases, and gastric acid is more likely to reflux into the esophagus or even the throat. According to statistics, about 40% of chronic rhinitis patients have GERD, and the symptoms are more obvious at night.
- Reflux stimulation: Gastric acid and pepsin will destroy the barrier function of the nasal mucosa, making it more susceptible to allergens and pathogens, leading to worsening symptoms such as nasal congestion and runny nose.
- Nerve reflex: Reflux stimulates the throat nerves, which may cause nasal mucosal vasodilation and increased glandular secretion through nerve reflex, further aggravating the symptoms.
Scientific response: From adjusting sleeping posture to improving the environment, a multi-pronged approach to relieve nighttime symptoms
For the reasons why rhinitis worsens at night, the following measures can be taken to relieve discomfort:
- Raise the head: Raise the head of the bed by 15-20 cm when sleeping, and use gravity to reduce nasal mucosal congestion and secretion retention.
- Control allergens: Wash bedding with hot water above 55°C every week, use anti-mite bedspreads; avoid pets from entering the bedroom; regularly clean air conditioning filters and humidifiers.
- Adjust humidity: Use a humidifier to maintain indoor humidity at 40%-60% to avoid dry nasal mucosa; if combined with asthma, the humidity must be controlled not to exceed 50%.
- Nose rinse before bed: Clean the nasal cavity with saline or special rinse solution to remove allergens and secretions and reduce nighttime irritation.
- Treatment of gastroesophageal reflux: If combined with symptoms such as acid reflux and heartburn, you need to consult a doctor to adjust your diet (such as avoiding eating before bedtime and reducing high-fat foods) or use acid-suppressing drugs.
Rhinitis worsens at night as a result of multiple factors. Understanding its mechanism helps to take targeted measures. If the symptoms continue to affect sleep or quality of life, it is recommended to seek medical attention in a timely manner, identify the cause through allergen testing, nasal endoscopy, etc., and develop an individualized treatment plan.
