Fig. 2
From: Serum melatonin concentration in critically ill patients randomized to sedation or non-sedation
Mean melatonin concentration throughout the 4-day study period including 95% confidence interval. X axis; day and time of the sample (e.g., 2–14 = day 2 time 14:00). The reference curve is hypothetical and based on the literature, mainly M. Karasek et al. and demonstrates mean concentration of melatonin diurnal variation among healthy individuals in the age group of the study population [5, 12, 19]