Briseis had decided on an early night, having plans to go shoot something in the park at dawn. (She'd not yet decided what. She was hoping inspiration would strike when she was standing there with her camera.)
She wasn't actually yet asleep when her buzzer went off... and off and off and off.
No one kept ringing like that if it wasn't something serious.
She pulled herself out of bed and darted across the apartment to press the button. "Who's there?" she asked.