I assume most of you had parents who ragged on you to make your bed every morning or most of us getbiggers just had our fat mexican maids do it. Think about this.
When you sleep you sweat and shed skin all night. By making your bed you're trapping that sweat and skin with a big warm comforter and letting it incubate all day in a dark warm environment. Leaving the top sheets off let's your bed sheet dry up and allows air to flow over cleaning up all of the dead skin and crap.
Best to not make your bed and leave the top sheets off to let your bed breathe during the day.
Let's consider some possible motivations behind their advice:
1. Perhaps every glimpse of disorder exacts a small aesthetic cost, slowly erasing their sanity.
2. They may desire to instill discipline, choosing this simple and attainable goal to do so.
3. The mindful parent may be wary of instilling neuroses, particularly fear of invisible and practically unquantifiable ills
4. Due to the difficulties inhering in assessing risk of this kind (cf. point 3), the parent may find herself fully relieved after employing any countermeasure whatever, e.g. regular washing
5. Washing, laundry, etc. if not sufficient, in itself, to abnegate one's fear of filth, may serve in aggregate tip the scales, by dint of (2).
