Quoting: silverwaterlady
I personally wouldn’t build a loft so low one can’t stand up. gcrank1 wrote many of the reasons why.
House Hunters on Hulu has a bunch of small house people on the search. You could watch to see what a low loft is like to navigate.
A lot of people build lofts and find out they don’t like sleeping in them because it’s much hotter no matter what time of year and end up using them for storage.
If sleeping in a loft is your only choice, make sure you add a window. You are going to need it to vent out heat.