Mean and standard deviation for PSQI at the end of the study. Vitamin D group: 6.75 (2.97) Placebo group: 9.73 (3.04) Cohen's D: 0.99 (>0.8 is regarded a larg

Mean and standard deviation for PSQI at the end of the study. Vitamin D group: 6.75 (2.97) Placebo group: 9.73 (3.04) Cohen's D: 0.99 (>0.8 is regarded a large effect size) Side note: The translation "Petersburg’s Sleep Index" instead of "Pittsburgh Sleep Quality Index" just cracks me up though! =)