Plymouth-based Select Comfort, aka Sleep Number, topped the J.D. Power's second annual mattress satisfaction survey.

Sleep Number also topped J.D. Power's first mattress satisfaction survey last year.

"Our customers' satisfaction is the direct result of our team's dedication and passion to improving lives by delivering unparalleled sleep experiences," said Shelly Ibach, Select Comfort president and chief executive officer in a company statement.

J.D. Power, a consumer intelligence and data analytics company, surveyed 2,622 customers who purchased beds within the last 12 months and ranked mattress companies on a 1,000 point scale.

Greg Truex, senior director of the At-Home practice at J.D. Power, said that while Sleep Number remained at the top of the list there was a "little bit of jostling between the brands ranked two through six."

Sleep Number scored 887, one point higher than Simmons/Beautyrest and 32 points higher than the average score of 855.

J.D. Power measured seven factors to arrive at its overall mattress satisfaction score. In order of importance those factors were: comfort, price, support, durability, variety of features, warranty and contact with customer service.

According to J.D. Power Sleep Number scored particularly well on the warranty and features factors.

"Mattress selection may be more complex than consumers think," Truex said in the release. "By educating themselves about available options, they can add features to their purchase and increase satisfaction. Simultaneously, if manufacturers and salespeople effectively highlight add-ons, the price-per-purchase will increase along with satisfaction."

Customer satisfaction with mattress brands appears to be improving. According to the survey results the average score among mattress brands rose to 855, up from 835 last year.

J.D. Power may be best known for its car ratings but the Costa Mesa, Calif.-based company rates products in other categories including Homes. In its Homes category J.D. Power also measures customer satisfaction in kitchen and laundry room appliances and 10 other home improvement categories that include mattresses, kitchen cabinets, paint retailers, and smart thermostats among others.

While Sleep Number finished on top of the mattress category as a "best in class" company Truex said Sleep Number also compares very favorably with "best in class" companies from the other At Home categories.

In describing why it's important to measure satisfaction among mattress buyers Truex pointed out that mattresses can be among the more expensive and important purchases in the homes category. A recent first-time homeowner Truex knows first hand the complexities involved in making a mattress purchase. "There is a lot to consider, to have a third party source in J.D. Power for the consumer and that benchmark for the industry, it just seemed like a natural fit that J.D. Power would get involved," Truex said.