At his Newark, N.J., factory, Michael Hammer, chief executive officer of Shifman Mattress, sees all the evidence he needs to be convinced the economy is on the rebound.

Workers are busy filling orders for the company’s premium mattresses, some of which sell for as much as $20,000 for a queen-size mattress and box-spring set. Sales jumped 42 percent in January, compared with the same month a year earlier, and year-to-date sales increased 30 percent over the same period in 2009.

“We’re still down a little from 2008, but let me tell you, it’s fabulous,” Hammer said. “You have no idea the difference we’ve seen this year.”

Sales of mattresses, which sagged as the economy slumped, are expected to increase 4.5 percent this year, and 6.3 percent in 2011, according to the International Sleep Products Association. Previous recessions have shown that when economic downturns end, mattress sales turn up again.

“The rebound years tend to be very good for the mattress industry,” said Ryan Trainer, president of the International Sleep Products Association. And because the slump was deeper in 2008 and last year than previous recessions, manufacturers and retailers are hoping the bounce-back effect also will be bigger than ever.

“Mattress sales are certainly one of the more deferrable purchases consumers have,” Trainer said. “It’s not like your auto, where if you blow a tire or your carburetor goes out you need to address those right away. A used mattress can be tolerated for a while. As we end the recession, we will start seeing more pent-up consumer demand coming to the market.”

Much of that demand is expected to come from the luxury-bedding customer who postponed big-ticket purchases while stock portfolios were shrinking.

Earl Kluft, whose California factory makes the Aireloom and the Kluft luxury brands — the priciest of which sells for $33,000 for a king-size set — said his sales increased almost 50 percent in the first quarter over a year ago, and that he expects sales to top $40 million in 2010. Prices in the Kluft line begin at about $13,000.

Bloomingdale’s began carrying the Kluft mattresses in 2006. Bloomingdale’s sells only premium mattresses and features three luxury brands in its showrooms — Kluft, Shifman, and Stearns & Foster.

At Bloomingdale’s, luxury mattress sales held up better during the recession than lower-priced models, said mattress buyer Bryan Umiker. “The luxury business, while it did weaken, didn’t weaken by as much as our middle and lower-end mattress business did,” he said. “And beginning in the summer of 2009, we saw the luxury customer start coming back in strength.”

The Kluft and Shifman brands, Umiker said, are “both made by smaller, lesser-known companies with the highest attention to detail and quality, with a real passion for bringing better-end luxury product to the market.”

The two brands, he said, make mattresses the old-fashioned way, mostly by hand. Both brands are made exclusively in the United States. “The average $1,500 luxury queen mattress in this country probably takes anywhere from 20 to 25 minutes to produce,” Umiker said. “When you talk about Shifman and Kluft, you’re talking about a production cycle that can range from three hours to 18 to 24 hours, depending on just how much hand craftsmanship goes into it.”

Hammer was eager to show visitors the process.

“Get ready: You’re going to see the world’s best mattress being made,” Hammer said as he showed visitors around the factory in the Ironbound section of Newark, built in the 1870s, where Shifman mattresses have been made since 1915. The company was founded in Newark in 1893.

Before 2008, Shifman sales were booming, growing at about 20 percent a year for more than a decade.

The company employs 50 workers, many of whom have been with Shifman more than 20 years. In 2008, the company expanded its factory to boost production, adding 24,000 square feet to the existing 60,000-square-foot building. Shifman moved into the new section in November 2008, just as the economy crashed.

“It wasn’t such a great time to expand,” said Bill Hammer, Michael’s son and the president of Shifman. “But now we’re in a great position to respond to increased demand.”