Objective: To investigate the changes in water content in the lumbar intervertebral discs by quantitative T2 MR imaging in the morning after bed rest and evening after a diurnal load. Materials and Methods: Twenty healthy volunteers were separately examined in the morning after bed rest and in the evening after finishing daily work. T2-mapping images were obtained and analyzed. An equally-sized rectangular region of interest (ROI) was manually placed in both, the anterior and the posterior annulus fibrosus (AF), in the outermost 20% of the disc. Three ROIs were placed in the space defined as the nucleus pulposus (NP). Repeated-measures analysis of variance and paired 2-tailed t tests were used for statistical analysis; with p < 0.05 as significantly different. Results: 12 values significantly decreased from morning to evening, in the NP (anterior NP = -13.9 ms; central NP = -17.0 ms; posterior NP = -13.3 ms; all p < 0.001). Meanwhile 12 values significantly increased in the anterior AF (+2.9 ms; p = 0.025) and the posterior AF (+5.9 ms; p < 0.001). 12 values in the posterior AF showed the Largest degree of variation among the 5 ROIs, but there was no statistical significance (p = 0.414). Discs with initially Low T2 values in the center NP showed a smaller degree of variation in the anterior NP and in the central NP, than in discs with initially high 12 values in the center NP (10.0010 vs. 16.1%, p = 0.037; 6.4% vs. 16.1%, p = 0.006, respectively). Conclusion: Segmental quantitative T2 MRI provides valuable insights into physiological aspects of normal discs.