8 mo is a dangerous age for falling out of bed. At about that age, dd only slept between us in the bed. When dh got up for work, he put up the siderail on his side of the bed. For naps, I'd put her in the playpen to sleep. My dd would crawl over pillows and was always a good roller even before she could crawl. When the playpen nap idea stopped working, I put the bed mattress on the floor and stored the base. dh was NOT happy about that but I remember another baby dying by falling on the floor and suffocating (never leave pillows, blankets lying on the floor beside the bed) so I was pretty terrified at the time. I don't think the danger is so much in the fall (well depending on the height and the surface), the fall probably isn't going to be life threatening, it's the suffocation risk. You just have to constantly update your sleeping arrangements to keep up with their new abilities.