Rest-activity rhythm

The circadian rhythm — the daily cycle of sleep and activity — has made the headlines following a new study of 6,621 adults from the NHANES, which found a −65% association with all-cause mortality. However, this figure does not relate to the circadian rhythm in isolation, but rather to the combination of a «strong rhythm plus sufficient activity» compared with the worst-performing group. Let’s examine where the science lies and where there is mere speculation, and what this means…