Plenty of people cannot fall asleep without a fan running, and then wake up with a scratchy throat, a blocked nose and gritty eyes, and blame the weather. The fan is usually the cause, and the fix is almost never turning it off. It is changing the aim, the distance and how long it runs.
Why you wake up congested
Nasal passages and eyes depend on a moist surface. Hours of moving air over a face dries that surface, and the body responds by producing more mucus, which feels exactly like a stuffy nose. Dust and dander stirred up from the floor add to it if you have allergies.
Aim across the bed, not at the bed
Point the airflow so it passes over your body rather than into your face, and put a few feet of distance between the fan and your pillow. That single change resolves most complaints. A bedside model from a listing such as https://socoolfan.net/ works better on a dresser across the room than on the nightstand.
Use the timer you paid for
Falling asleep is when you need the airflow and the noise. Two hours later you do not, and the fan is drying you out through the deepest part of the night. A shutoff timer solves the problem completely and saves battery on a portable unit.
Why the white noise works
Steady broadband sound raises the floor so that a slamming door or a passing truck no longer stands out against silence. Your brain reacts to changes in sound, not to sound itself, which is why a constant hum helps and an intermittent one does not.
Where masking becomes a problem
- Keep the volume low enough that a smoke alarm still wakes you.
- In a nursery, place any sound source well away from the crib and keep it soft.
- Parents of newborns should still be able to hear the baby breathing.
- Do not use a fan to cover a noise you could fix with a door sweep.
- If you need it louder every month, get your hearing checked.
The draft myth
A fan blowing on you does not give you a cold. Colds are caused by viruses, and no amount of moving air creates one. What airflow can do is dry your airways and stiffen a shoulder you left uncovered, which is enough to convince people otherwise.
Fan death is not a thing
The old story about a fan in a closed bedroom being fatal has no mechanism behind it. A fan in a sealed room does not consume oxygen or generate anything toxic. The only real risk is heat, and it appears only when the room air is already dangerously hot.
The setup worth copying
Fan across the room, aimed over the foot of the bed, lowest speed that you can hear, timer set for ninety minutes, a glass of water on the nightstand. Add a clean intake grille, because a dusty fan is louder and moves less air than the same fan wiped down.