Question

Circadian rhythms can best be described as heartbeats that trigger a change in blood circulation. the regulation of biological cycles into regular, daily patterns. the time between sunrise and sunset, which determines sleep patterns. the changes that occur in wakefulness after jet lag and shift work.

Answer 1

The answer would be: the regulation of biological cycles into regular, daily patterns

Circadian rhythm is not only related to the sleep pattern but also some of the other hormones that control the metabolisms like cortisol and melatonin. The rhythm also defines the body temperature fluctuation. The duration of the cycle should be around 24 hours which follow the duration of one day.