Sleepy’s, the Long Island mattress retailer that was bought by Mattress Firm, which was in turn gobbled up by a South African company, says in a regulatory notice that it will lay off 28 employees at its Hicksville headquarters.

The layoffs, in the company’s finance and accounting unit, could begin as early as Dec. 31 and extend to April, according to the WARN notice posted Friday.

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The reductions come after Sleepy’s was purchased in February by competitor Mattress Firm Holding Corp. in Houston. And last month, South African retail giant Steinhoff announced it was buying Mattress Firm.

“The reduction in jobs . . . is a result of Mattress Firm’s efforts to realize efficiencies by reducing duplicative jobs created through Mattress Firm’s acquisition of Sleepy’s,” said Jody Putnam, Mattress Firm’s talent and integration officer.

Putnam said the company would offer employees severance packages and job-placement services.

At the time of the purchase by Mattress Firm, Sleepy’s, which was a family-owned business with roots dating to 1931, had about 3,400 employees overall, including those at its more than 1,000 stores and other facilities. Its website showed about 40 stores on Long Island.

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Under WARN, New York’s Worker Adjustment and Retraining Notification Act, companies with at least 50 full-time employees must give them at least a 90-day notice of a mass layoff or closing.