Funny to come across this as it's a long-standing problem for me. My take is that I'm usually too depressed to care about showering or brushing my teeth. But if I'm hypomanic I'm too busy to shower or brush my teeth. Either way I'm f*cked. Plus by the time I'm hypomanic I'm so used to not showering much that it doesn't seem important because it's already a habit not to shower regularly. About to get a root canal so maybe that will teach me a lesson about dental hygiene (the vicodin is quite nice but not worth the expense of a root canal).