Why should you not open the window when sleeping at night?

Many people have the habit of opening the window when sleeping because the fresh air from outside makes them feel cool and comfortable. Especially in the countryside or quiet places with little traffic, the fresh air from outside helps people fall asleep easily.

However, health experts advise against opening the window when sleeping at night because this can have a negative impact on the body. Cold air itself does not cause colds or flu - diseases caused by microorganisms attacking the body, overwhelming the human immune system - but it can dry out the nasal cavity, leading to increased mucus production and leading to sinus and throat infections.

On the other hand, in big cities and along crowded roads with heavy traffic, opening the window will reduce the quality of indoor air. In addition, car horns, dog barking, and the screams of “night owls” will also affect your sleep.

Here are some specific reasons why you should not open your windows when sleeping at night:

Closing the windows helps block out noise

If you live in a noisy environment and have trouble sleeping, it is better to close the windows when you go to bed. A quiet space is the ideal place to help you sleep well, deeply, and more securely. Opening the windows will amplify the noise, which can disturb your sleep as well as affect your health in the long term.

Avoid insomnia due to cold

If you open the windows when you sleep, you may not be able to sleep soundly because of the cold. In particular, if you have a cold and leave the windows open on autumn and winter nights, you may take longer to recover from the flu. When you are cold and your body is busy keeping warm, it fights off pathogens less effectively.

Avoid the risk of allergies

Opening windows at night puts you at risk of exposure to allergens from outside and making it easier to inhale them while you sleep,

“Pollen levels are typically higher during the day when plants release pollen into the air, but there is evidence that pollen levels in the air can also be higher at night,” explains Dr. Laren Tan, a pulmonologist and director of the Comprehensive Obstructive Airway Disease Program at Loma Linda University in the US.

Spring and fall are particularly hot, as allergens, dust, and particulate matter (like those in air pollution or those from wildfires) drift in, triggering allergies and asthma. “Allergies and asthma can cause the body to produce more mucus, making it harder to breathe and coughing more,” says Dr. Tan.

Allergies and asthma can also disrupt sleep, weaken the immune system, and make you more susceptible to other unrelated illnesses. That's why you shouldn't open the windows when you sleep at night, especially for people with allergies.

It's better to ventilate the room during the day, vacuum and clean the house.

Avoid mold growth

Depending on the outside and inside temperatures, opening the windows at night can also increase the risk of mold, especially when the outside temperature drops sharply at night and the bedroom cools down during this time.

Therefore, you should not open the windows when you go to bed at night and only open the windows wide the next morning to regulate the air in the room.

Regardless of whether you close or open the windows at night, you should ventilate all rooms 3-5 times a day, each time for about 10 minutes (if it's cold outside, 5 minutes is enough). To cool the air in the room again and improve the quality of sleep, you should ventilate right before going to bed.

In addition to regular ventilation, you can improve air quality by turning off electrical appliances, heaters, and air conditioners at night. This habit will also reduce your electricity bill.

If the humidity in the room is too high due to excessive sweating at night, you can put a dehumidifier in the bedroom. If you have trouble sleeping because of dry air, hang a few damp towels near your bed. Dry air often causes nasal congestion, difficulty sleeping, or waking you up many times during the night.