Had this for dd (although a chair underneath with a desk and not sofa), and the metal slats were horrific to sleep on. Her one and only sleepover on it had the 2 girls ending up on same bed as it was too painful to lie on (they were only 6 at the time so weight wasn't an issue).
ooooh, tootired - thank you for linking to my thread! Was wondering if it was bad form to do it myself . Can confirm that the slats are wooden and are very comfortable to sleep on - have done so myself several times.