Make a mental note to take a sick day come Jan. 10. It'll be Michigan's "most miserable day of the year," according to mattress review and comparison site, which claims to have researched 30 years of weather data.

The company looked at Michigan's expected coldest and darkest days and averaged them to pinpoint the "most miserable day of the year."

Statistically, Michigan's coldest day is expected to be Jan. 29, with a temperature of 23 degrees, and its darkest day will be Dec. 22, with 1.4 kWh of solar energy, according to the research. Solar energy represents the amount of visible light and ultraviolet radiation reaching the ground.

Averaging those two terrible factors will make Jan. 10 the dreariest day of the year for Michiganders.

So you've been warned. Have the blankets, fuzzy pajamas and hot chocolate handy to battle the winter doldrums.

The "most miserable day" will differ across the country, so check out the map below to see when it will hit each state.

Created by Sleepopolis View larger version

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