48 hour sleep deprivation with the DRL birds. Top shows response rate (responses/minute), center shows number of reinforcers acquired, and bottom shows the behavioral inhibition ratio (reinforcers/responses). Data shown are organized by season, Sleep deprivation decreased response rate regardless of season. The letters a, b, and c indicate statistical differences between DRL performance during the sleep deprivation compared to Pre Sleep Deprivation. Pre Sleep Deprivation performance did not differ statistically from Recovery or Post Recovery for any season, although average response rates during Post Recovery were about 25% (Winter) or 50% (Spring) higher than during Pre Sleep Deprivation. N = 15. Error bars represent half of the 95% CI.