When the temperature drops in North Dakota, the furnace runs around the clock. What most people don’t realize is that the same heating system keeping them warm is also silently pulling moisture from the air, and from their eyes. Dry eye symptoms often spike during winter months not just because of the cold outside, but because of the dry, heated air inside. Burning, scratchiness, and blurred vision are all signs your tear film is struggling to keep up.

At Vision Source Mandan, we see an increase in dry eye complaints each winter, and heating is one of the most common contributing factors. Dr. Brittany Schauer, Dr. Wayne Aberle, and Dr. Danielle Dyke work with patients year-round to identify what’s driving their symptoms and find solutions that actually work in the real conditions of North Dakota living.

What Heating Does to Indoor Air

Furnaces, baseboard heaters, and space heaters are designed to warm air, but in doing so, they dramatically reduce indoor humidity. Cold outside air already holds less moisture, and once it enters your home and gets heated, the relative humidity can drop well below comfortable levels. A study published through the National Institutes of Health found that indoor humidity is positively associated with dry eye metrics, suggesting low-humidity indoor environments can worsen symptoms and signs of the condition.

When humidity drops below 40%, the tear film on your eye’s surface begins to evaporate faster than it can be replenished. The result is a cycle of irritation that many patients describe as constant and hard to escape, because they’re spending most of their time indoors.

The Connection Between Airflow and Tear Evaporation

Forced-air heating systems don’t just dry the air; they also move it. Vents positioned near desks, beds, and seating areas direct warm, dry air directly at your face. Even ceiling fans running in winter to redistribute heat can accelerate tear evaporation. These are environmental triggers that compound each other throughout the day and night.

Patients who wake up with gritty, uncomfortable eyes often have a bedroom vent nearby or sleep in a room with the heat running high all night. If you’re experiencing red or itchy eyes in the morning, your heating setup may be a key factor.