Mattress retailer Sleepy’s has signed a lease for 3,454 square feet of space at 151 Merrimack St. in Boston.

151 Merrimac is a six-story, 42,476-square-foot retail and office building acquired by Cambridge-based Transatlantic Investment Management in May 2014 for $13.5 million. Avison Young represented the seller, Causeway Industries Trust, in that transaction. The building’s anchor tenant, Mass General Hospital, leases 58 percent of the building square’s footage. 

Avison Young Principal Karyn McFarland represented Transatlantic and will continue to serve as the building’s exclusive leasing representative. Peter Lyons of the Dartmouth Company represented Sleepy’s in the transaction. The store is scheduled to open in spring 2015.

"Sleepy’s recognized that the enormous growth in the North Station area represents a huge potential," Anthony Goschalk, President of Transatlantic, said in a statement.

Retailers have been attracted to the neighborhood because of the pace of residential development, with more than 3,000 multifamily units completed in recent years or in the pipeline.