BEVERLY, Mass. — Christine Matthews woke up at 3:30 a.m. with one of her kids on Monday and never went back to sleep, creating an 18-hour workday with few breaks. Not typical, but not rare, either.

Such working conditions may explain why she challenges the findings of a study released yesterday that says a full-time stay-at-home mother would earn the equivalent of $134,121 a year if paid for all she does.

“I don’t even think that’s close,” said the Danvers mother of twins. “I would say double that amount.”

The survey elicited laughs from mothers, who found it amusing that someone attempted to calculate the worth of changing diapers, washing clothes and breaking up wrestling matches all day long., the Waltham-based compensation experts, interviewed 400 mothers online over the last two months to reach the salary figure. They calculated the earning power of the 10 jobs that respondents said most closely comprise a mother’s role — housekeeper, day-care teacher, cook, computer operator, laundry machine operator, janitor, facilities manager, van driver, chief executive and psychologist.

Stay-at-home mothers reported working an average of 91 hours a week, including 22 hours as a housekeeper.

Beverly Farms resident Kim Fogelgren, the mother of a 3-month-old and 4-year-old, said she never realized how around-the-clock the work of motherhood is until she became one herself.

“It’s a funny concept, to think of throwing a dollar value at it,” she said. “But what I think they are saying is that stay-at-home moms work hard. I’m just glad I have the opportunity to do it. I wouldn’t trade it for the world.”

Based on the interviews, the survey also determined that mothers who work outside the home would earn an extra $85,876 a year on top of her wages for the work she does at home.

Salem resident Patti Morsillo said she found it odd that in 2006, the survey didn’t attempt to calculate what a father should make based on his contributions to the family. She said she knows many very involved fathers, including ones who have made a decision to stay at home to watch their children.

Morsillo is the stay-at-home mother of a 12- and 13-year-old who’s been “on the other side of the fence,” too. The $134,000 salary proposed for her current job doesn’t make her feel any more valuable.

“I know that it’s right for me,” she said.

Matthews, who personally prefers the term “domestic goddess” to stay-at-home mother, agreed that it’s not about the money.

“In my estimation, you can’t put a monetary figure on it,” she says. “What you are giving your kids is priceless.”

Susan Flynn writes for The Eagle-Tribune in North Andover, Mass. Material from Reuters was used in this report.