The Low Loft Bed. Specifically designed for rooms with sloping ceilings. You can't get lower than this bed, but at the same time it still frames that mattress for an attractive modern addition to your bedroom.
I am not a carpenter and this was my first attempt....you may want to put some slots in the solid wood panel under your bed. This will reduce the chances of your mattress going mouldy. Or just air your mattress outside occasional. I work in a bed shop and mouldy mattresses can happen quite quickly with moisture and heat.