Very cool graphic with some very normal flaws. As Somno says your body puts more emphasis on Stage 3/4 and so should you. There is a reason why our bodies get the majority of its slow wabe sleep prior to even one minute of REM. I would have also like to see something on the swing in length of stage 3 and REM as the night progresses.
Consistant sleep is the most effective sleep. When you maintain a normal and constant sleep shedule your body will adjust it's sleep cycles to fit that routine.