diarism

diary +‎ -ism

diarism (uncountable)

1. The practice of writing a diary.
   • 2007, Elif Batuman, The Windmill and the Giant: Double-entry Bookkeeping in the Novel‎:

     Double-entry bookkeeping, and the concurrent rise of the European paper industry led to new writing practices — graphomania, diarism, and obsessive spiritual confession — and to a balance-oriented worldview […]

• midairs, sidarim