answer and explain - basicq

[ArchivalUser]

A 21-year-old student who is part of a study of circadian rhythms, sleeps in a cave for one month with no access to clocks or watches. At the end of
the month, the length of her circadian cycle is likely to be closest to
(A) 21 hours
(B) 22 hours
© 23 hours
(D) 24 hours
(E) 25 hours

[ArchivalUser]

25 hours babyq
Thats what the natrual timing of human brain is.

[ArchivalUser]

lol, thats unfair, my brain needs 25 hours a day then! im only getting 24..)

[ArchivalUser]

Hi basicq
I agree with Sammy. Light and dark are cues to our bodies to keep resetting the timing of the suprachiasmatic nucleus or nuclei (SCN) of the hypothalamus. Therefore, in the absence of light, the circadian rhythm will follow the timing of the SCN, known as the master clock. And that endogenous rhythm (when it is not reset) is slightly more than 24 hours.
So, I would go with E...25 hours.

Thanks for the questions. We keep you busy, don't we?

[ArchivalUser]

thanks mledr ...this q is very strange for me...
so SCN is our master clock with 25 hrs