Marathon recovery and chess tournament preparation

I spent last week recovering from the Two Rivers marathon. I experienced a sleep nirvana like no other. For four nights in a row, I slept straight through the night, with loads of deep sleep (according to my FitBit), and for 1-2 hours longer than usual. I would have expected that with no running, I wouldn't need so much sleep, but it was like my body knew it was recovering from a major event and the sleep was phenomenal. FitBit even gives you a sleep score, and one night I got a 90, which is the...