Effect of time of day and partial sleep deprivation on plasma concentrations of IL-6 during a short-term maximal performance

The present study was designed to evaluate the effect of time of day and partial sleep deprivation (PSD) on short-term maximal performance and level of interleukin-6 (IL-6) in trained subjects. In a randomized order, 12 football players were asked to perform a 30-s Wingate test during which we measured the peak (PP) and mean (MP) powers. Measurements were performed at 0800 and 1800 hours, after two nocturnal regimens: (1) a reference normal sleep night (RN) and (2) 4 h of PSD caused by an early awakening. Plasma IL-6 concentrations were measured before (P1), immediately after (P2), and 60 min after the exercise (P3). PP and MP improved significantly from the morning to the afternoon after RN (P < 0.05) and from the afternoon to the morning after PSD (P < 0.05). Compared to RN, PP and MP were not affected by PSD the following morning. However, there was a significant decrease in PP and MP (P < 0.001) after the PSD at 1800 hours. In all conditions, IL-6 and resting core temperature were significantly higher (P < 0.05) in the afternoon than in the morning. In all sessions, IL-6 levels increased significantly from P1 to P2 (P < 0.01) and remained elevated in the afternoon during the recovery period after PSD (P < 0.05). However, no significant difference was observed in IL-6 between P1 and P3 during RN and PSD at 0800 hours. In conclusion, a short-term high-intensity exercise may increase the IL-6 concentrations in the morning and the afternoon. Moreover, IL-6 remained elevated during the recovery period in the afternoon after the PSD at the end of the night.