Per Rebel1:
Any caffeine that enters my body comes from chocolate or green tea.
I don't drink coffee or sodas (Pepsi, Coke, etc.). And on that day, I may have had one green tea at breakfast, 16 ...

Then my money is on the observations of Ed Pawlowski and Shadow.

Long, long ago and far, far away after a day of surfing I'd lay down to
catch a little sleep before work and I would feel the motion of the
waves as I lay there with eyes closed.
--
Pete Cresswell