Is the rain getting you down? You're not alone.
But a new study has found the weather isn't the biggest contributor to the winter blues. The length of the day - the time between sunrise and sunset - is far more important.
"On a rainy day, or a more polluted day, people assume that they'd have more distress. But we didn't see that," says Mark Beecher, clinical professor and psychologist.
"We looked at solar irradiance, or the amount of sunlight that actually hits the ground. We tried to take into account cloudy days, rainy days, pollution, but they washed out. The one thing that was really significant was the amount of time between sunrise and sunset."
The study came about through chance.
"Mark and I have been friends and neighbours for years, and we often take the bus together," says Lawrence Rees, physics professor at Brigham Young University.
"Of course you often talk about mundane things, like how are classes going? How has the semester been? How 'bout this weather? So one day it was kind of stormy, and I asked Mark if he sees more clients on these days. He said he's not sure, it's kind of an open question. It's hard to get accurate data."
Prof Rees had that data, and they had an idea.
"We realised that we had access to a nice set of data that not a lot of people have access to," says Prof Beecher.
"So Rees said, 'Well, I've got weather data,' and I'm like, 'I've got clinical data. Let's combine the pair!' Wonder Twin powers activate, you know?"
The data covered weather minute-by-minute in the areas where Prof Beecher's clients lived, so they were able to find out exactly what conditions prompted people to seek psychological help.
Nothing correlated, except the amount of daytime - it didn't matter whether it was raining, cloudy or sunny.
The research has been published in the Journal of Affective Disorders.Newshub.