biological clock
noun /ˌbaɪəˌlɒdʒɪkl ˈklɒk/
/ˌbaɪəˌlɑːdʒɪkl ˈklɑːk/
(specialist)- a natural system in living things that controls regular physical activities such as sleeping
- (figurative) At 35, Kate's biological clock was ticking (= she was beginning to think that she would soon be too old to have children).
- The movements of the leaves are triggered by the plant’s biological clock.
- With jet lag, your biological clock is out of synch with the actual time.