We find an "inverse found money effect" in two-person public good experiments in which individuals earning their endowments contribute more and engage in "altruistic conditional cooperation" when they are matched with those whose endowment is provided by the experimenters.

We administer an online Guessing Game collecting responses across all 24 h of the day. While time-of-day itself does not affect guesses, when including trait-level sleepiness and previous night sleep, adverse sleep states lead to responses significantly farther from equilibrium.