Thank you for the compliment.
Where there is uncertainty about when the bleeding began – as is generally the case when one wakes up with bleeding – the calculation of the
onah is based on the time the bleeding is discovered. Thus, a woman who awoke after sunrise and found blood on her underwear would consider her period to have started during the day. A woman who noticed blood on a sanitary napkin after sunset, and did not feel the wetness during the day, would consider her period to have started at night.
In addition, the onah is based on the time in which a blood flow began, and not on any earlier staining, whether or not the staining caused
niddah.