Maybe I should call it more a "rule of thumb."
We know lots of "rules of thumb:"
When you race (running), no long runs or speedwork for as many days as there were miles in your race.
After a race or long run, calories don't count for as many hours as there were miles run.
And so on.
I have a theory that I think I will develop into a new personal rule of thumb:
For each hour in a hard effort (i.e., long run or ride, race, speedwork), an extra hour of sleep per hour of effort will enhance recovery.
For the 16 hours and 20 minutes I was on the course at IMFL, I needed to "replace" 16 hours of sleep. Not all at once. Maybe an hour a day for 16 days. I didn't do this religiously, since I thought of it about a week later, but I had been going to bed earlier each night just because I was tired. This was when the "hour of sleep per hour of effort" idea dawned on me.
A 6-hour marathon, then, would suggest 5 days of sleeping an hour extra per night (or day.)
For a hard 10K effort, extra sleep for however long that took.
Maybe, any training effort that we're still tired from an hour or so later, or the next day, should trigger the "sleep alarm" -- however long that effort lasted, get its equivalent in extra sleep.
It might not always be possible.
It might not be indispensable.
But it couldn't hurt.