Your biological clock is your body's way of registering time. It does not rely on events such as day or night, but on factors such as your habits, your age, and chemical changes taking place in your body.
For women, the 'biological clock' governs the time for having children.
biological clock in British English
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
See also circadian
biological clock in American English
1.
any of the various natural cycles in organisms that are related to the tides, sun, moon, light, temperature, etc. and that control breeding, feeding, migration, etc.
2. Informal
a person's life cycle; specif., the period of human fertility
her biological clock was ticking away
Examples of 'biological clock' in a sentence
biological clock
What keeps biological clocks on time?
Mayes, Kathleen Beat Jet Lag - arrive alert and stay alert (1991)
Another factor recently being studied is the influence of the body 's biological clock.
Christianity Today (2000)
My biological clock may be missing, but my canine clock is acute.
Times, Sunday Times (2013)
Other products are planned to help to gauge the ticking of a woman 's biological clock.