Human sleep rhythm

[drnsmith]

I have recently read that the free-running period (FRP) for the 'daily' rhythms is close to 25.5 hours and that it is entrained by a circadian exogenous cue (day/night light/dark).

I am curious about the origin of the FRP and what the significance of a periodicity of greater than 24 hours might represent.

Thanks,

Darren Smith

[zami'87.]

Well probably it was important to be aware of seasons...at winter nights are longer(temperature can change quickly but lenght of night not)...believe that it affected on reproduction(maybe when the conditions are appropriate for raising offspring)