Gaussian distribution of the data wil be tested by the Kolmogorov-Smirnov test. Data will be presented as mean ± standard deviation (SD). Comparisons between shifts will be made with ANOVA. Relationships between data will be assessed by Pearson correlation. Significance will be accepted at the p<0.05 level. Statistical procedures will be performed using SPSS Advanced Statistics software (SPSS Inc., Chicago, IL).