Period question?

ok so its the eigth day of my period and this morning i only saw a tiny dot of blood in my pad then i put a panty liner in this morning and a little while later i look aat it and it a rlly big blotch and yesterday when i was about to change my pads from the night before and it was not that big then a few hours later it was rlly huge why is my period lighter at night then during the day