CIRCADIAN VARIABILITY OF BILIRUBIN IN HEALTHY MEN DURINGNORMAL SLEEP AND AFTER AN ACUTE SHIFT OF SLEEP

摘要

Bilirubin is a laboratory test widely used for patient care, especially neonatal patientsand patients with anemia or suspected liver disorders. Bilirubin has also been shown tobe associated with sleep pattern and oxidative stress. The aim of this study was to inves-tigate the variation of bilirubin in a group of healthy individuals with normal nightsleep as well as during acutely displaced sleep, as sleep timing varies immenselybetween individuals while clinical samples are still mainly taken in the morning. Westudied the diurnal variation of bilirubin during night-sleep and day-sleep conditionsin seven healthy volunteers. Serum samples were collected every hour (50 samples/individual) to evaluate the effect of different sampling times and sleep displacement onthe test results. The mean acrophases (peak time) occurred at 10.6 h during the night-sleep condition and at 18.4 h during the day-sleep condition. The diurnal intraindivi-dual variation was high during both the night-sleep and day-sleep conditions, withcoefficients of variation (CV) in the range of 12.8 to 42.5%. The diurnal variation washigher during the day compared to night-sleep condition. Thus, bilirubin samplingshould be restricted to the morning, preferably after a normal night sleep, to minimizeintraindividual variation.