[lucb1e]

In response to both parents of this comment, my first reaction would be that "of course" it's personal: maybe your bed at home is not that great, or a neighbouring mine makes sounds that don't register consciously anymore but still keep you up. But then again, in my experience it is a personal thing beyond a person's environment. I know people of both kinds and the location does not seem to matter.

It's often the case in non-exact science studies that the results are difficult to reproduce. Besides the obvious "they're not called exact", it's interesting. What is this caused by? Would, in this example, some people lack the 'feature' of sleeping with half a brain?