The degree of punishment assigned to criminals is of pivotal importance for the maintenance of social order and cooperation. Nonetheless, the amount of punishment assigned to transgressors can be affected by factors other than the content of the transgressions. We propose that sleep deprivation in judges increases the severity of their sentences. We took advantage of the natural quasi-manipulation of sleep deprivation during the shift to daylight saving time in the spring and analyzed archival data from judicial punishment handed out in the U.S. federal courts. The results supported our hypothesis: Judges doled out longer sentences when they were sleep deprived.