The chronic stress of training and frequent travel during the competitive soccer season may adversely affect sleep and thus, recovery in collegiate athletes. PURPOSE: To examine the relationship between changes in sleep, inflammatory biomarkers, and exercise energy expenditure (EEE) throughout the season. METHODS: DI female soccer players (N=24) were monitored throughout the competitive season. During all training and games, EEE (kcal/kg) was evaluated using an integrative GPS and heart rate monitoring system, which was individualized based on pre-season performance testing. Pittsburgh Sleep Quality Index (PSQI) questionnaires, weight assessments, and blood draws were completed prior to preseason and at weeks 2, 4, 8, & 12 of the season. Total cortisol (TCORT), free cortisol (FCORT), c-reactive protein (CRP), IL-6, and TNFα were analyzed. Change scores were calculated between timepoints for each biomarker, GlobalPSQI, Sleep Duration (SD), and Sleep Quality (SQ) scores. Pearson product correlations were conducted between change scores as well as EEEAVG between timepoints with significance set at p<.05. RESULTS: ΔGlobalPSQI was not related to any measures, except ΔSD and ΔSQ (r=.39, r=.51; p<.05). ΔSD and ΔSQ were both significantly correlated to ΔIL-6 (r=-.21, r=-.23; p<.05). ΔIL-6 was positively correlated to ΔCRP (r=.32, p<.05), ΔTNFα (r=.43, p<.05), and ΔFCORT (r=.26, p<.05). ΔCRP was also significantly related to ΔTCORT (r=.24, p<.05). EEEAVG was not associated with any measures (p>.05). CONCLUSIONS: There appears to be a relationship, albeit weak, between sleep measures and IL-6, with increased SD and SQ (i.e. decreased PSQI score) related to increases in IL-6. Additionally, increased IL-6 was associated with increases in other proinflammatory and stress markers, potentially indicative of fuel mobilization and physiological repair responses. The cumulative load of the competitive season could indicate an increased need for recovery, thus yielding compensatory increases in SD and perceived SQ. Further research is warranted using objective sleep measures to examine the observed relationship in soccer players. Funding provided by Quest Diagnostics