biological clock

My "biological clock" won't run down for another century or more yet!

They could no longer set their biological clocks in response to light.

Maybe a little bit of the biological clock is ticking?

"My biological clock is running out," she announced one evening.

It means, she said, that "the biological clock gets turned back."

"I could see what comes from settling for somebody or listening to your biological clock."

With so many time zone shifts he had little idea what his own biological clock was doing.

Many more genetic components of the biological clock are now known.

And with female athletes, the question often involves the old biological clock.

I'm beginning to think there must be a biological clock for grandmothers.