biological clock

[ bahy-uh-loj-i-kuhl klok ]

noun

, Physiology.

1. Also called bod·y clock [bod, -ee klok]. an innate mechanism of the body that regulates its periodic cycles or biorhythms, such as the sleep-wake cycle. chronotype ( def ), circadian ( def ).
2. an innate mechanism regulating the passage of an organism through the natural stages of its life, especially with reference to the reproductive stage of a woman's or man's life or the approaching end of this stage:

   My biological clock is ticking, but I don't feel ready to have kids!

biological clock

noun

1. an inherent periodicity in the physiological processes of living organisms that is not dependent on the periodicity of external factors
2. the hypothetical mechanism responsible for this periodicity

biological clock

/ bī′ə-lŏj′ĭ-kəl /

1. An internal system that controls an organism's circadian rhythms, the cycles of behavior that occur regularly in a day. In mammals, the biological clock is located near the point in the brain where the two optic nerves cross. In many birds, the biological clock is located in the pineal gland. In protists and fungi, the individual cells themselves regulate circadian rhythms.

biological clock

1. The innate rhythm of behavior and body activity in living things. A twenty-four-hour cycle of body activity, which operates in some organisms, is called the circadian rhythm .

Notes

Although the term biological clock refers to all innate timing mechanisms, it is often used when describing certain body functions that are subject to this rhythm, such as the loss of fertility with age.

Word History and Origins

Origin of biological clock¹

First recorded in 1950–55

Example Sentences

It’s also not going to make it easier to go to sleep way before your natural biological clock, or circadian rhythm, says it’s time.

From Time

In the days after daylight saving time starts, our biological clocks are a little bit off.

From Vox

The gradual shortening of days until the winter solstice messes up our circadian rhythm, the biological clock that takes note of daylight hours and regulates sleep, appetite, body temperature, heart rate and hormone production.

From Popular-Science

Bryn Woznicki, a 33-year-old filmmaker who lives in Los Angeles, has always known she wants to be a mother, “but every year,” she says, “it’s a ticking time bomb working against your biological clock.”

From Time

In shift workers, researchers want to test the impact of resetting their biological clocks to a standard day-night schedule.

From Time

I've never had any regrets and must have not come equipped with the mythical biological clock.

From The Daily Beast

Before the fertility revolution, it was the alarm on the biological clock that rang at about age 35.

From The Daily Beast

She now made plans to marry and have a child just as her biological clock was ticking toward never.

From The Daily Beast

"Stress is basically a biological clock," Singer told The Daily Beast.

From The Daily Beast

Related Words

• circadian rhythm