This time of year, domestic tranquility hovers somewhere between "Brrrrr" and "Grrrrr."

With overnight temperatures slipping into the 40s, many households confront the question of when to turn on the furnace. Newlyweds might think this is a simple call. They would be wrong.

"Every year my wife turns the [heat] on around the time our daily high temps only reach to 75," said Eric Davis of Minneapolis. That usually means early September, which makes him crazy, and even a little ill. "There's always a burning, dusty smell in our house the first time the heat kicks on. I always get some sort of sinus condition after the fact."

Davis has, on occasion, responded by sneaking into the basement and turning off the furnace system.

"She doesn't know where the furnace switch is located, so she can't do anything about it," he said. "And I've removed the batteries from the gas fireplace's remote control, or altogether hidden the remote control."

All of which sound like actions that would generate some heat.

Patrick Pfundstein of St. Paul said temperatures inside his home have to drop to 50 degrees before he even begins to consider turning on the furnace. "Probably helps explain my single status," he added. Once the heat is on, he sets the thermostat at 60 degrees, but he'll "maybe go wild and 65 on the weekends."

He said it's not a matter of saving money, but of metabolism — a circumstance that comes up with curious consistency.

Why do women always complain that they're chilly? Why do men always grouse that the house is too warm? When Freud proclaimed, "Anatomy is destiny," had his wife just edged toward the thermostat?

Why women hog the blankets

Turns out there's some science to the shivering.

In the mid-1800s, a German doctor, Carl Reinhold August Wunderlich, determined that the average adult has a body temperature of 98.6 degrees. Women, however, generally had slightly higher body temps — about one-third of a degree.

Still, the standard was established, even inspiring a 1967 hit song by one-hit wonder Keith: Hey, 98.6, it's good to have you back again. (Apologies for the earworm.)

In 1998, researchers at the University of Utah looked into why women, even with higher body temperatures, are more likely to feel cold. In fact, they found that women's hands were consistently 3 degrees colder than men's hands.

The explanation lies in how men and women differ in terms of size, weight and proportion.

Men tend to have more heat-generating muscle than women, researchers said, while women tend to have more heat-retaining fat than men.

Fat insulates internal organs at the expense of extremities — fingers and toes. So while women technically may have warmer hearts, if their toes are freezing, they feel cold.

Yes, yes, this isn't as much about gender as body type. An article in the online magazine Mental Floss this year observed that if everyone was the same size and weight, "people of all genders should experience temperature in similar ways. Women are, however, more likely to be smaller, and smaller people are more likely to be colder."

Staving off the season

Xcel Energy has no statistics on when most switches get flipped because the decision is so dependent upon personal preference, spokeswoman Patti Nystuen said. One person's arctic blast is another's refreshing briskness.

There's another, more psychological reason that some resist the inevitable: As long as the furnace remains off, it's still late … late … summer. Right?

Barb Schaller of Burnsville said she can't turn on the furnace yet out of principle, "but we do most certainly turn on the [gas] fireplace for about 90 minutes in the morning to take the chill out," mostly because she likes sleeping with a window open about 4 inches.

Then again, some just can't resist a dare.

Jeremy Scheller of Minneapolis said he and three college classmates once tested their limits "in a dump of an apartment in northeast Minneapolis."

He explained, "Three out of four of us banded together to not turn on the furnace until January 1st. You could see your breath when you went to bed at night, but it was a great college challenge."

The one who didn't sign on for the misery?

"He wasn't pleased, but went along with things," Scheller said. The experiment actually lasted until Jan. 1, a milestone that outshone even the fact that their apartment was burgled on New Year's Eve.

"I remember vividly coming home to my roommate saying we got robbed, but at least we can turn on the heat now."