Was out all afternoon so didn't get any chance for a nap. I had a couple of glasses of Diet Coke, which was not good but there were so few real alternatives and I was in the mood. Anyway, I didn't feel any extraordinary caffeine high or withdrawal. But I didn't feel sleepy either.
Felt a bit of tiredness in the legs from yesterday's run.
At home, I did my usual SL stuff and went to bed at midnight with an alarm for 0445 even though I had had no nap.
Woke up at 0445. Took a lot of will power to wake up.
Energy levels: 90% reduced to 80% later.