Tonks just stood there watching Grindelwald's back until he disappeared from view.
Sleep? Yeah, maybe that was the best idea. Maybe if she went back to sleep, she'd wake up in her own bed and realise that she'd just been having some sort of bizarre dream.
She turned around and retraced her steps to the house that she'd come out of and crawled back into the bed, covering her head with her pillow.
Wait 'til she told her friends that she'd dreamed about Gellert Grindelwald!