Circadian rhythms can be affected to some degree by almost any kind of external time cue, such as the beeping of your alarm clock, the clatter of a garbage truck , or the timing of your meals.

• 生物钟节律在一定程度上可以受任何外界时间线索影响，如闹钟的声音清洁车的声音及进餐的定时等。