We should note that, yes, it’s still important to hydrate during the summer. But let’s revisit that psychological marker we referenced above: Because you might associate sweat with needing to drink more water, in the winter (when you typically don’t sweat as much), the urge to drink may get put on the back-burner.

However, just because you might not be sweating as much, doesn’t mean you aren’t losing fluids. As Cohen explains, dehydration takes a different route during winter: “It’s not because you’re outside and sweating so much; it’s that indoor environment in the winter we don’t take into account.” 

See, there’s less humidity (aka, water in the air) during the winter. And when you crank up the heat in your home, it creates an environment that literally sucks the moisture out of your body. It’s the same logic as why your skin loses more water in the winter (a process called transepidermal water loss). Ever wake up with a dry, scratchy throat or chapped lips? Yep, that’s your arid environment doing it’s thing.