As the crown prince/ss of the kingdom, it was already expected that your siblings will do anything just to take the throne from you.

Which includes the idea of you getting assassinated in your own chambers in the middle of the night...

“It's nice to see you, your Highness.. Or perhaps i should say it was?” An assassin said as he towered over you, with a knife in hand.

Perhaps it was good that you stayed up late..