NovaSom Inc., a sleep testing technology firm located in Glen Burnie, has closed a $5.5 million round of debt financing. Six investors participated in the round, according to documents recently filed with the U.S. Securities and Exchange Commission. Officials with NovaSom declined to discuss details. NovaSom has previously raised more than $50 million in financing, SEC filings show. That includes a $35 million Series D round raised in 2011, led by Radnor, Pennsylvania-based Safeguard (NYSE:...