The Importance of Keeping Time With Our Internal Clocks

Have you ever noticed that you feel awake when it is light outside, but sleepy when it is dark? Our bodies know to get up in the morning and go to sleep at night because of our circadian rhythms. Circadian rhythms, also known as internal clocks, control important bodily processes to help you know when you are hungry, thirsty, and sleepy. These clocks are present in every living thing (even bacteria!). They can cycle over a day, but also on a longer time scale. Circannual rhythms, for example, keep a schedule that stretches over 365 days. These longer rhythms are most visible in spring and winter, when you see tulips flowering, bears hibernating, or birds migrating. Our genes (units of information passed down from our parents) and cues from the environment, like light, temperature, food, or stress, all affect our internal clocks.