An airplane is not the most comfortable place in the world: You're trapped with dozens of people in an airborne sardine can, where something as simple as making your way to the bathroom can be a monumental struggle.
One of the biggest contributors of discomfort on a flight is the freezing temperature: It's normal to have your body quivering from the blasts of cool air circulating the cabin — and you can be straight out of luck if you forget to bring a sweater.
Turns out, in-flight temperatures are kept low for an unexpected reason. According to a study published in American Society for Testing and Materials, high cabin pressure and temperature may increase the chance of fainting for passengers. Being on an overheated plane also heightens the risk of nausea and dehydration. Since so many humans are packed closely within a confined space, there's already plenty of heat generated by our bodies. The definition of overheating is different for each person, so the cabin crew keeps the interiors of a plane cooler to err on the side of caution. A temperature below 90°F is the general industry standard.
The age of the aircraft you're traveling is another factor for low cabin temperature: According to a retired Delta captain interviewed by Traveller, older planes have a bigger tendency to be chilly, due to their less developed air conditioning systems. The newer models are equipped with advanced thermostats that can adjust temperatures in parts — or even specific rows — of the cabin.
So, what's the best way to deal? The number one way to prevent freezing on your next flight would be to pack on the layers. If that doesn't work, don't be afraid to speak up to the flight attendant politely. Cabin temperatures are typically controlled by the cockpit crew, so if it's way too cold — a member of the staff might be able to make a difference.