I've experimented with elevated sleeping platforms before and have built 3 other elevated beds, each improving on design and functionality. Here's the latest design, using 3 sheets of plywood and incorporating:
In addition to the inset base to prevent stubbed toes, the mattress deck was also designed to allow the mattress to sit slightly over the decking, giving your knees and shins a soft surface to touch, not hard frame.
Here's how I made a smart and simple bed frame with only 3 sheets of plywood.
Using inexpensive 3/4"- 4'x8' (20x1220x2440mm) plywood I was able to make this bed frame from 3 sheets. I used inexpensive plywood as much of this structure is not going to be seen, and the portions that are will be painted and at floor level.
Using CAD software to design the frame, I started by measuring the dimensions of my queen size mattress. I wanted a continuous deck for my mattress to lie on top of, since the mattress was larger than one sheet of plywood I spanned it over 2 sheets.
Next I measured how tall I wanted by bed frame to be and made the side and end pieces to match the mattress deck. To utilize the space under the bed I designed drawers on each side of the bed frame, the drawer cut outs and components were arranged inside the sheets. To secure the bed from any sheer forces I also designed an internal brace to fit inside and provide stability.
All the components were arranged onto the plywood sheets in CAD to make an efficient cut plan. I used a simple notching at the edges to give a solid connection.
CAD drawing included, feel free to use or modify