I know my period's coming when I started having problems with sleep approx ~6 days ago.
Maybe more? I don't remember.
I'd sleep late and wake early.
Then I started getting easily irritated, or easily emotional.
I feel nervous.
Not forgetting the random thoughts of wanting to hurt myself.
There's also the sudden disinterest in things.
They don't persist, but they do happen.

Period came two days ago,
I've been sleeping alot on the 2nd day due to the exhaustive nature of the cramps.
but on the 2nd night to the 3rd, I wasn't able to sleep for abit
and I woke up early on the 3rd day, today.