Circadian rhythms dictate the 24-hour shifts in gene expression, protein levels, and various cellular processes throughout the day, such as melatonin affecting our sleep-wake cycle. Such changes in cell activity—in particular, cyclical changes in metabolism— can greatly influence the effectiveness of a drug and the severity of its side effects, depending on when it is administered.
However, each individual has unique circadian timing, with "body time" being offset by as much as 6 hours between people, making it difficult—if not impossible—for doctors to take into account when giving drugs. Previous attempts to assess a person's body time have relied on intense, repeated sampling procedures that were impractical for clinical applications. But in a study, published yesterday (August 27) in Proceedings of the National Academy of Sciences, researchers have demonstrated a new method that requires only two blood samples, taken 12 hours apart.
"Due to a combination of genetics and environment, ...
