The hour before everyone else is up is not productive, and I have stopped trying to make it so. I tried writing in it, planning in it, clearing email in it. Each attempt turned the hour into a smaller version of the working day.
What it is good for is harder to describe. Reading a few pages with no aim. Watching the light arrive on the wall opposite. Writing one line in the notebook, if a line turns up.1
1 If no line turns up, the notebook stays shut. Forcing it defeats the purpose.
Protecting it
The hour survives only if nothing is allowed to claim it in advance. No reminders set for six fifteen, no promise to finish something before breakfast. It is the one hour in the day with nothing written against it, and that blankness is exactly what it is for.