Chronotherapy is especially relevant when the risk and/or intensity of disease symptoms vary predictably over time, as is the case for allergic rhinitis, arthritis, asthma, myocardial infarction, congestive heart failure, stroke, and peptic ulcer disease.34 The present study identified salivary ARRB1 as a candidate circadian biomarker that might contribute to the future use of chronotherapeutic strategies. This evidence concerns the gene ARRB1 and congestive heart failure.