As I get older, I’m starting to realize the importance of getting enough sleep. Sometimes, I start coughing right as I’m falling asleep, and it wakes me back up. It’s incredibly frustrating.
I was born in southern China, and I've spent most of my life living there. When I was living at home, I rarely coughed during my sleep—or at least, it wasn't very noticeable. After graduating, I moved to Beijing, where the nighttime coughing became much more frequent. At the time, I blamed it on air pollution and cat dander (yes, I had a cat!). After about half a year, I decided to leave Beijing and began my master's degree in Switzerland.
My first year there was fine. Maybe it was because our dormitory was right by a lake, or perhaps I just didn't have much stress. Our classes were fun and relaxed; even though the final exams were hard, you only really stressed about them for a day. Because of this, I didn't experience many sleep issues.
During my second year, I started an internship and moved to Interlaken. My apartment was near a farm. Sleep became much more important to me because I needed full energy for work the next day. However, I noticed my coughing becoming more frequent again, and I had no clue why. At first, I blamed the temperature—winters in Interlaken are chilly—so we turned on the heater. But I still woke up coughing. Then, I blamed the farm, thinking maybe some tiny airborne particles were drifting into our room. We kept the doors and windows closed all day, but by the end of my internship, I still hadn't found the real cause and kept waking up in the middle of the night.
Later, I moved to Calgary, Canada, and the exact same thing happened. I’d read the theory that sleeping in a cool room helps you fall asleep faster, but for me, the colder the room, the worse my cough gets. So, I started researching what exactly was happening. Below are a few possible reasons:
1. The "Dry Air" Tickle Cool air naturally holds less moisture than warm air. In a place that already has a highly arid, dry climate like Calgary, cooling a bedroom down can strip almost all the remaining humidity out of the air. When breathing in cold, dry air, it rapidly dries out the vocal cords and the lining of the throat and lungs. The airways are highly sensitive to this drying effect and interpret it as an irritation, triggering a sudden, dry cough reflex to "clear" the airway.
2. Gravity and Postnasal Drip Throughout the day, your nose and sinuses produce mucus that drips down the back of your throat and is swallowed without you even noticing. The trigger for your cough occurs when you lie down, as gravity stops helping that mucus drain and it instead pools at the back of your throat. The cold temperature makes this worse because breathing in cool air causes the nose to produce extra mucus—much like how your nose runs on a chilly winter day. All of this extra mucus collects in your throat, tickling the nerves and triggering a coughing fit the moment your head hits the pillow.
3. Silent Acid Reflux Even if you do not feel traditional "heartburn," lying down flat removes gravity's ability to keep stomach acid down. Micro-amounts of acid can travel up the esophagus and irritate the back of the throat or the vocal cords. The body instantly coughs to protect the lungs from the acid. If you tend to eat your batch-cooked meals or a snack shortly before going to bed, this could be the culprit. (Not likely the main reason for me, since I seldom eat before going to sleep).
4. Cold-Induced Airway Spasm For some people, cold air acts as a direct irritant to the lungs. When the cold air hits the bronchial tubes, they undergo a mild spasm and temporarily constrict (often called a reactive airway). This makes you feel a sudden tightness or tickle in your chest, followed by a persistent cough.
How to Fix It
Running a humidifier is often the magic bullet for this issue. Placing a cool-mist humidifier next to your bed adds the moisture back into the air that the cooler temperature stripped away, which keeps your throat and airways lubricated.
You can also elevate your head using an extra pillow to raise your head and upper shoulders by just a few inches. This uses gravity to stop both the postnasal drip and any stomach acid from pooling in your throat.
Additionally, make an effort to breathe through your nose. Your nasal passages are designed to act as a built-in HVAC system that warms and humidifies cold air before it reaches your lungs. If you breathe through your mouth at night, that cold air hits your throat directly and causes irritation.
Finally, having a warm drink before bed can make a big difference. Drinking a small cup of warm, decaffeinated tea or hot water with honey right before lying down gently coats and soothes the throat, making your nerves much less hyper-reactive.