We’ve all been there… You’re visiting family or friends and they’ve got a full house. As bedtime approaches, they say, somewhat sheepishly, “We’ve got you on the sleeper sofa.” And as others head off to comfortable beds, you take the cushions off the couch, pull up on the compressed “mattress,” and listen as the clanking bars and squeaking springs tell you what you already know: you’re in for a long, sleepless night, and probably a morning of aches and pains.