Influence of circadian rhythm on the efficacy of the hepatitis B vaccination

Vaccination is the most effective way to protect HBV infection [1,2]. Many factors (genetic features, gender, HLA structure, obesity, smoking and T cell subgroups) may influence response to the hepatitis B vaccination [3]. Generally, events affecting the immune system can be expected to have an effect on the response to vaccination. The daylight cycle constitutes the circadian rhythm in human beings. The suprachiasmatic nucleus in the hypothalamus serves as a circadian clock. The immune system also exhibits a circadian rhythm [4]. The major influence of the circadian rhythm on cellular and humoral immune response is mediated by cortisol and melatonin in humans [5]. Hence, it was hypothesized that vaccination given in the morning or in the evening might affect the immune response to the vaccine. Since no previous studies in the literature related with the subject have been found in English, the influence of daily circadian rhythm on hepatitis B vaccination was investigated in this study.