Honestly, I wouldn't worry about it. All toddlers are needles of a clock. Unless they are in a bunk bed , which I wouldn't suggest til they are way older, they figure it out. Toddler beds are usually low anyways but you can put some pillows on the floor or use those removable ikea rails.
@Sheri i looked at those beds that's what I wanted to get for him but the pediatrician said he doesn't want him that close to the floor cuz of his allergies and any spec of dust that will set him off.
@Karla his crib converts into a twin size bed so I think the height is regular not low...but I should double check that
Mine does this too. She's in a bunk bed and sleeps on the bottom, which is basically a floor bed. She's rolled off a couple times and still managed to stay asleep lol. Hasn't hurt herself or anything. I stuffed my giant c shaped pregnancy pillow under her sheets so that keeps her in bed. You can get him one of those montessori floor beds instead of bed rails. It's basically a giant floor crib.