Lehrer S. Rats on 22.5-hr light:dark cycles have vaginal
opening earlier than rats on 26-hr light:dark cycles. J Pineal Res
Rats on 22 .5-hr light:dark cycles had vaginal opening significantly
rats on 26-hr light:dark cycles. This finding might explain the early menarche
in blind girls: Their circadian rhythms, like those of rats on 22.5-hr cycles,
might be more rapid than normal. Thus a set number of cycles can occur in a
shorter time than usual, allowing puberty to take place early.